This is meant to be a compilation of abstracts from the Proceedings of 'Advancing Astrophysics with the SKA' (AASKA14). Since it was done following the series of avalanches and weak after-shocks, it may not be complete, so should you find it is not complete, please contact me at: hmessias[at]oal.ul.pt ------------------------------------------------------------------------------ \\ arXiv:1412.6942 Date: Mon, 22 Dec 2014 11:57:46 GMT (1kb) Title: Proceedings of 'Advancing Astrophysics with the SKA' (AASKA14) - Continuum Science' Chapters Authors: I. Prandoni, N. Seymour ('SKA Continuum Science' Working Group) Categories: astro-ph.GA Comments: 18 of the 20 'Continuum Science' Chapters are available here \\ This is the collection of Chapters on 'Continuum Science' presented at the Conference 'Advancing Astrophysics with the SKA' (AASKA14), held in Giardini Naxos (Italy), June 9-13, 2014 \\ ( http://arxiv.org/abs/1412.6942 , 1kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5664 Date: Wed, 17 Dec 2014 22:49:41 GMT (1176kb) Title: The SKA view of cool-core clusters: evolution of radio mini-halos and AGN feedback Authors: Myriam Gitti, Paolo Tozzi, Gianfranco Brunetti, Rossella Cassano, Daniele Dallacasa, Alastair Edge, Stefano Ettori, Luigina Feretti, Chiara Ferrari, Simona Giacintucci, Gabriele Giovannini, Michael Hogan, Tiziana Venturi Categories: astro-ph.CO astro-ph.GA Comments: 17 pages, 5 figures. To appear as part of 'Continuum Science' in Proceedings of "Advancing Astrophysics with the SKA (AASKA14)", PoS(AASKA14)076 \\ In about 70% of the population of relaxed, cool-core galaxy clusters, the brightest cluster galaxy (BCG) is radio loud, showing non-thermal radio jets and lobes ejected by the central active galactic nucleus (AGN). In recent years such relativistic plasma has been unambiguously shown to interact with the surrounding thermal intra-cluster medium (ICM) thanks to spectacular images where the lobe radio emission is observed to fill the cavities in the X-ray-emitting gas. This `radio feedback' phenomenon is widespread and is critical to understand the physics of the inner regions of galaxy clusters and the properties of the central BCG. At the same time, mechanically-powerful AGN are likely to drive turbulence in the central ICM which may also play a role for the origin of non-thermal emission on cluster-scales. Diffuse non-thermal emission has been observed in a number of cool-core clusters in the form of a radio mini-halo surrounding the radio-loud BCG on scales comparable to that of the cooling region. Large mini-halo samples are necessary to establish their origin and connection with the cluster thermal properties and dynamics, especially in light of future X-ray characterization of the cluster cores as it is expected by Athena-XIFU. We show that All-Sky reference survey at Band 2 with SKA1 at confusion limit (rms ~2 {\mu}Jy per beam) has the potential to detect up to ~620 mini-halos at redshift z<0.6, whereas Deep Tier reference surveys at Band 1/2 with SKA1 at sub-arcsec resolution (rms ~0.2 {\mu}Jy per beam) will allow a complete census of the radio-loud BCGs at any redshift down to a 1.4 GHz power of 10^{22} W/Hz. We further anticipate that SKA2 might detect up to ~1900 new mini-halos at redshift z<0.6 and characterize the radio-mode AGN feedback in every cluster and group up to redshift z ~1.7 (the highest-z where virialized clusters are currently detected). \\ ( http://arxiv.org/abs/1412.5664 , 1176kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5868 Date: Thu, 18 Dec 2014 14:24:40 GMT (1862kb,D) Title: Galaxy Cluster Science with the Sunyaev-Zel'dovich Effect Authors: Keith Grainge, Stefano Borgani, Sergio Colafrancesco, Chiara Ferrari, Anna Scaife, Paolo Marchegiani, S. Emritte, J. Weller Categories: astro-ph.CO Comments: To appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the Square Kilometre Array' PoS(AASKA14)170 \\ Studying galaxy clusters through their Sunyaev-Zel'dovich (SZ) imprint on the Cosmic Microwave Background has many important advantages. The total SZ signal is an accurate and precise tracer of the total pressure in the intra-cluster medium and of cluster mass, the key observable for using clusters as cosmological probes. Band 5 observations with SKA-MID towards cluster surveys from the next generation of X-ray telescopes such as e-ROSITA and from Euclid will provide the robust mass estimates required to exploit these samples. This will be especially important for high redshift systems, arising from the SZ's unique independence to redshift. In addition, galaxy clusters are very interesting astrophysical systems in their own right, and the SKA's excellent surface brightness sensitivity down to small angular scales will allow us to explore the detailed gas physics of the intra-cluster medium. \\ ( http://arxiv.org/abs/1412.5868 , 1862kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5940 Date: Thu, 18 Dec 2014 16:58:27 GMT (671kb) Title: Cluster Radio Halos at the crossroads between astrophysics and cosmology in the SKA era Authors: R. Cassano, G. Bernardi, G. Brunetti, M. Br\"uggen, T. Clarke, D. Dallacasa, K. Dolag, S. Ettori, S. Giacintucci, C. Giocoli, M. Gitti, M. Johnston-Hollitt, R. Kale, M. Markevitch, R. Norris, M. Pandey-Pommier, G.W. Pratt, H. R\"ottgering, T. Venturi Categories: astro-ph.CO Comments: 13 pages, 6 figures, to appear in proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)073 \\ Giant Radio Halos (RH) are diffuse, Mpc-sized, synchrotron radio sources observed in a fraction of merging galaxy clusters. The current scenario for the origin of RHs assumes that turbulence generated during cluster mergers re-accelerates pre-existing fossil and/or secondary electrons in the intra-cluster-medium (ICM) to the energies necessary to produce the observed radio emission. Moreover, more relaxed clusters could host diffuse "off state" halos produced by secondary electrons. In this Chapter we use Monte Carlo simulations, that combine turbulent-acceleration physics and the generation of secondaries in the ICM, to calculate the occurrence of RHs in the Universe, their spectral properties and connection with properties of the hosting clusters. Predictions for SKA1 surveys are presented at low (100-300 MHz) and mid (1-2 GHz) frequencies assuming the expected sensitivities and spatial resolutions of SKA1. SKA1 will step into an unexplored territory allowing us to study the formation and evolution of RHs in a totally new range of cluster masses and redshift, allowing firm tests of the current theoretical hypothesis. In particular, the combination of SKA1-LOW and SUR will allow the discovery of ~1000 ultrasteep- spectrum halos and to detect for the very first time "off state" RHs. We expect that at least ~2500 giant RHs will be discovered by SKA1-LOW surveys up to z~0.6. Remarkably these surveys will be sensitive to RHs in a cluster mass range (down to ~1014 solar masses) and redshifts (up to ~1) that are unexplored by current observations. SKA1 surveys will be highly competitive with present and future SZ-surveys in the detection of high-redshift massive objects. \\ ( http://arxiv.org/abs/1412.5940 , 671kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5643 Date: Wed, 17 Dec 2014 21:56:16 GMT (103kb) Title: Radio investigation of Ultra-Luminous X-ray Sources in the SKA Era Authors: Anna Wolter (1), Anthony P. Rushton (2 and 3), Mar Mezcua (4), David Cseh (5), Fabio Pintore (6), Isabella Prandoni (7), Zsolt Paragi (8), Luca Zampieri (9) ((1) INAF-Osservatorio Astronomico di Brera, Milano (2) University of Oxford, (3) University of Southampton, (4) Instituto de Astrofisica de Canarias, (5) Radboud University, Nijmegen, (6) Universit\`a degli Studi di Cagliari, (7) INAF-IRA Bologna, (8) JIVE, Dwingeloo, (9) INAF-Osservatorio Astronomico di Padova) Categories: astro-ph.GA Comments: 13 pages, 2 figures; to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)' \\ A puzzling class of exotic objects, which have been known about for more than 30 years, is reaching a new era of understanding. We have discovered hundreds of Ultra Luminous X-ray sources (ULXs) - non-nuclear sources with X-ray luminosity in excess of the Eddington luminosity for "normal" size stellar Black Holes (BH) - and we are making progresses towards understanding their emission mechanisms. The current explanations imply either a peculiar state of accretion onto a stellar size BH or the presence of an intermediate mass BH, the long-sought link between stellar and supermassive BHs. Both models might co-exist and therefore studying this class of object will give insight into the realm of accretion in a variety of environments and at the same time find look-alikes of the primordial seed BHs that are thought to be at the origin of todays supermassive BHs at the centre of galaxies. The radio band has been exploited only scantily due to the relative faint fluxes of the sources, but we know a number of interesting sources exhibiting both extended emission (like bubbles and possibly jets) and cores, as well as observed transient behaviour. The new eras of the SKA will lead us to a major improvement of our insight of the extreme accretion within ULXs. We will both investigate in detail known sources and research new and fainter ones. When we have reached a thorough understanding of radio emission in ULX we could also use the SKA as a discovery instrument for new ULX candidates. The new array will give an enormous space to discovery: sources like the ones currently known will be detected in a snapshot up to 50 Mpc instead of at 5 Mpc with long, pointed observations. \\ ( http://arxiv.org/abs/1412.5643 , 103kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5677 Date: Wed, 17 Dec 2014 23:42:42 GMT (123kb) Title: The Astrophysics of Star Formation Across Cosmic Time at $\gtrsim$10 GHz with the Square Kilometer Array Authors: Eric J. Murphy, Mark T. Sargent, Rob J. Beswick, Clive Dickinson, Ian Heywood, Leslie K. Hunt, Minh T. Hyunh, Matt Jarvis, Alexander Karim, Marita Krause, Isabella Prandoni, Nicholas Seymour, Eva Schinnerer, Fatemeh S. Tabatabei, Jeff Wagg Categories: astro-ph.GA Comments: 15 pages, 3 figures, to appear as part of 'Continuum Science' in Proceedings "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)085 \\ In this chapter, we highlight a number of science investigations that are enabled by the inclusion of Band~5 ($4.6-13.8$ GHz) for SKA1-MID science operations, while focusing on the astrophysics of star formation over cosmic time. For studying the detailed astrophysics of star formation at high-redshift, surveys at frequencies $\gtrsim$10 GHz have the distinct advantage over traditional $\sim$1.4 GHz surveys as they are able to yield higher angular resolution imaging while probing higher rest frame frequencies of galaxies with increasing redshift, where emission of star-forming galaxies becomes dominated by thermal (free-free) radiation. In doing so, surveys carried out at $\gtrsim$10 GHz provide a robust, dust-unbiased measurement of the massive star formation rate by being highly sensitive to the number of ionizing photons that are produced. To access this powerful star formation rate diagnostic requires that Band~5 be available for SKA1-MID. We additionally present a detailed science case for frequency coverage extending up to 30 GHz during full SKA2 operations, as this allows for highly diverse science while additionally providing contiguous frequency coverage between the SKA and ALMA, which will likely be the two most powerful interferometers for the coming decades. To enable this synergy, it is crucial that the dish design of the SKA be flexible enough to include the possibility of being fit with receivers operating up to 30 GHz. \\ ( http://arxiv.org/abs/1412.5677 , 123kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5743 Date: Thu, 18 Dec 2014 07:45:28 GMT (1228kb,D) Title: Astronomy below the Survey Threshold Authors: Jonathan T. L. Zwart, Jasper Wall, Alexander Karim, Carole Jackson, Ray Norris, Jim Condon, Jose Afonso, Ian Heywood, Matt Jarvis, Felipe Navarrete, Isabella Prandoni, Emma Rigby, Huub Rottgering, Mario Santos, Mark Sargent, Nick Seymour, Russ Taylor, Tessa Vernstrom Categories: astro-ph.GA astro-ph.CO astro-ph.IM Comments: 13 pages, 5 figures, to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)' [PoS(AASKA14)172] \\ Astronomy at or below the 'survey threshold' has expanded significantly since the publication of the original 'Science with the Square Kilometer Array' in 1999 and its update in 2004. The techniques in this regime may be broadly (but far from exclusively) defined as 'confusion' or 'P(D)' analyses (analyses of one-point statistics), and 'stacking', accounting for the flux-density distribution of noise-limited images co-added at the positions of objects detected/isolated in a different waveband. Here we discuss the relevant issues, present some examples of recent analyses, and consider some of the consequences for the design and use of surveys with the SKA and its pathfinders. \\ ( http://arxiv.org/abs/1412.5743 , 1228kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5753 Date: Thu, 18 Dec 2014 08:29:43 GMT (473kb,D) Title: The star-formation history of the Universe with the SKA Authors: Matt J. Jarvis (1,2), Nick Seymour (3), Jose Afonso (4,5), Philip Best (6), Rob Beswick (7), Ian Heywood (8,9), Minh Huynh (10), Eric Murphy (11), Isabella Prandoni (12), Eva Schinnerer (13), Chris Simpson (14), Mattia Vaccari (2), Sarah White (1) ((1) Oxford, (2) University of the Western Cape, (3) Curtin, (4) OAL, Lisbon, (5) Univ. Lisbon, (6) IfA, Edinburgh, (7) Manchester, (8) CSIRO, (9) Rhodes University, (10) UWA, (11) IPAC, Caltech, (12) INAF Bologna, (13) MPIA, (14) Liverpool John Moores) Categories: astro-ph.GA astro-ph.CO Comments: 19 pages, to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)068' \\ Radio wavelengths offer the unique possibility of tracing the total star-formation rate in galaxies, both obscured and unobscured. As such, they may provide the most robust measurement of the star-formation history of the Universe. In this chapter we highlight the constraints that the SKA can place on the evolution of the star-formation history of the Universe, the survey area required to overcome sample variance, the spatial resolution requirements, along with the multi-wavelength ancillary data that will play a major role in maximising the scientific promise of the SKA. The required combination of depth and resolution means that a survey to trace the star formation in the Universe should be carried out with a facility that has a resolution of at least ~0.5arcsec, with high sensitivity at < 1 GHz. We also suggest a strategy that will enable new parameter space to be explored as the SKA expands over the coming decade. \\ ( http://arxiv.org/abs/1412.5753 , 473kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5771 Date: Thu, 18 Dec 2014 09:26:27 GMT (266kb) Title: The Interplay between SF and AGN Activity, and its role in Galaxy Evolution Authors: Kim McAlpine, Isabella Prandoni, Matt Jarvis, Nick Seymour, Paolo Padovani, Philip Best, Chris Simpson, Daria Guidetti, Eric Murphy, Minh Huynh, Mattia Vaccari, Sarah White, Rob Beswick, Jose Afonso, Manuela Magliocchetti and Marco Bondi Categories: astro-ph.GA astro-ph.CO Comments: 16 pages, 3 figures to appear as part of "Continuum Science" in proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)083 \\ It has become apparent that active galactic nuclei (AGN) may have a significant impact on the growth and evolution of their host galaxies and vice versa but a detailed understanding of the interplay between these processes remains elusive. Deep radio surveys provide a powerful, obscuration-independent tool for measuring both star formation and AGN activity in high-redshift galaxies. Multiwavelength studies of deep radio fields show a composite population of star-forming galaxies and AGN, with the former dominating at the lowest flux densities (S$_{1.4\mathrm{GHz}}<$100~$\mu$Jy). The sensitivity and resolution of the SKA will allow us to identify, and separately trace, the total star formation in the bulges of individual high-redshift galaxies, the related nuclear activity and any star formation occurring on larger scales within a disc. We will therefore gain a detailed picture of the apparently simultaneous development of stellar populations and black holes in the redshift range where both star-formation and AGN activity peak (1$\leq$z$\leq$4). In this chapter we discuss the role of the SKA in studying the connection between AGN activity and galaxy evolution, and the most critical technical requirements for such of studies \\ ( http://arxiv.org/abs/1412.5771 , 266kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5793 Date: Thu, 18 Dec 2014 10:30:40 GMT (348kb) Title: Enabling the next generation of cm-wavelength studies of high-redshift molecular gas with the SKA Authors: J. Wagg (1), E. Da Cunha (2), C. L. Carilli (3 and 4), F. Walter (2), M. Aravena (5), I. Heywood (6 and 7), J. Hodge (8), E. Murphy (9), D. Riechers (10), M. Sargent (11), and R. Wang (12) ((1) SKAO, (2) MPIA, (3) NRAO, (4) Cavendish Laboratory, (5) Universidad Diego Portales, (6) CASS, (7) RATT, (8) NRAO, (9) Caltech, (10) Cornell University, (11) University of Sussex, (12) KIAA, Peking) Categories: astro-ph.GA Comments: 10 pages, to be published in Proceedings of Science: "Advancing Astrophysics with the Square Kilometre Array", PoS(AASKA14)161 \\ The Square Kilometre Array will be a revolutionary instrument for the study of gas in the distant Universe. SKA1 will have sufficient sensitivity to detect and image atomic 21 cm HI in individual galaxies at significant cosmological distances, complementing ongoing ALMA imaging of redshifted high-J CO line emission and far-infrared interstellar medium lines such as [CII] 157.7 um. At frequencies below ~50 GHz, observations of redshifted emission from low-J transitions of CO, HCN, HCO+, HNC, H2O and CS provide insight into the kinematics and mass budget of the cold, dense star-forming gas in galaxies. In advance of ALMA band 1 deployment (35 to 52 GHz), the most sensitive facility for high-redshift studies of molecular gas operating below 50~GHz is the Karl G. Jansky Very Large Array (VLA). Here, we present an overview of the role that the SKA could play in molecular emission line studies during SKA1 and SKA2, with an emphasis on studies of the dense gas tracers directly probing regions of active star-formation. \\ ( http://arxiv.org/abs/1412.5793 , 348kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5810 Date: Thu, 18 Dec 2014 11:25:25 GMT (4217kb,D) Title: SKA studies of nearby galaxies: star-formation, accretion processes and molecular gas across all environments Authors: R. J. Beswick (JBCA, Manchester), E. Brinks (Hertfordshire), M. A. Perez-Torres (IAA-CSIC), A. M. S. Richards (JBCA, Manchester), S. Aalto (Chalmers), A. Alberdi (IAA-CSIC), M. K. Argo (JBCA, Manchester), I. van Bemmel (JIVE/ASTRON), J. E. Conway (Onsala/Chalmers), C. Dickinson (JBCA, Manchester), D. M. Fenech (UCL), M. D. Gray (JBCA, Manchester), H-R. Klockner (MPIfR-Bonn), E. J. Murphy (IPAC, Caltech), T. W. B. Muxlow (JBCA, Manchester), M. Peel (JBCA, Manchester), A. P. Rushton (Oxford and Southampton), E. Schinnerer (MPIA-Heidelberg) Categories: astro-ph.GA astro-ph.CO Comments: 23 pages, 4 figures, to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the Square Kilometre Array' PoS(AASKA14)070 \\ The SKA will be a transformational instrument in the study of our local Universe. In particular, by virtue of its high sensitivity (both to point sources and diffuse low surface brightness emission), angular resolution and the frequency ranges covered, the SKA will undertake a very wide range of astrophysical research in the field of nearby galaxies. By surveying vast numbers of nearby galaxies of all types with $\mu$Jy sensitivity and sub-arcsecond angular resolutions at radio wavelengths, the SKA will provide the cornerstone of our understanding of star-formation and accretion activity in the local Universe. In this chapter we outline the key continuum and molecular line science areas where the SKA, both during phase-1 and when it becomes the full SKA, will have a significant scientific impact. \\ ( http://arxiv.org/abs/1412.5810 , 4217kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5827 Date: Thu, 18 Dec 2014 11:57:01 GMT (188kb) Title: Radio Observations of Star Forming Galaxies in the SKA era Authors: C. Mancuso, A. Lapi, Z-Y. Cai, M. Negrello, G. De Zotti, F. Perrotta, L. Danese Categories: astro-ph.GA Comments: 11 pages, 4 figures, to appear in proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)082 \\ We have combined determinations of the epoch-dependent star formation rate (SFR) function with relationships between SFR and radio (synchrotron and free-free) emission to work out detailed predictions for the counts and the redshift distributions of star-forming galaxies detected by planned Square Kilometer Array (SKA) surveys. The evolving SFR function comes from recent models fitting the far-infrared (FIR) to millimeter-wave luminosity functions and the ultraviolet (UV) luminosity functions up to z=10, extended to take into account additional UV survey data. We used very deep 1.4 GHz number counts from the literature to check the relationship between SFR and synchrotron emission, and the 95 GHz South Pole Telescope (SPT) counts of dusty galaxies to test the relationship between SFR and free-free emission. We show that the SKA will allow us to investigate the SFRs of galaxies down to few Msun/yr up to z=10, thus extending by more than two orders of magnitude the high-z SFR functions derived from Herschel surveys. SKA1-MID surveys, down to microJy levels, will detect hundreds of strongly lensed galaxies per square degree; a substantial fraction of them will show at least two images above the detection limits. \\ ( http://arxiv.org/abs/1412.5827 , 188kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5846 Date: Thu, 18 Dec 2014 13:13:54 GMT (52kb) Title: The physics of the radio emission in the quiet side of the AGN population with the SKA Authors: M. Orienti (1), F. D'Ammando (1,2), M. Giroletti (1), G. Giovannini (1,2), F. Panessa (3), ((1) INAF-IRA Bologna, (2) DIFA, University of Bologna, (3) INAF-IAPS Roma) Categories: astro-ph.GA Comments: 7 pages, to appear as part of 'Continuum Science' in Proceedings of 'Advancing Astrophysics with the SKA (AASKA14)' \\ Despite targets of many multiwavelength campaigns, the main physical processes at work in AGN are still under debate. In particular the origin of the radio emission and the mechanisms involved are among the open questions in astrophysics. In the radio-loud AGN population the radio emission is linked to the presence of bipolar outflows of relativistic jets. However, the large majority of the AGN population do not form powerful highly-relativistic jets on kpc scales and are characterized by radio luminosity up to 1023 W/Hz at 1.4 GHz, challenging our knowledge on the physical processes at the basis of the radio emission in radio-quiet objects. The main mechanisms proposed so far are synchrotron radiation from mildly relativistic mini-jets, thermal cyclo-synchrotron emission by low-efficiency accretion flow (like ADAF or ADIOS), or thermal free-free emission from the X-ray heated corona or wind. The difficulty in understanding the main mechanism involved is related to the weakness of these objects, which precludes the study of non-local radio-quiet AGN. Multifrequency, high-sensitivity radio observations are crucial to constrain the nature of the power engine, and they may help in distinguishing between the contribution from star formation and AGN activity. The advent of the SKA, with its sub-arcsecond resolution and unprecedented sensitivity will allow us to investigate these processes in radio-quiet AGN, even at high redshift for the first time. Both the broad-band radio spectrum and the polarization information will help us in disentangling between non-thermal and thermal origin of the radio emission. The jump in sensitivity of a few order of magnitudes at the (sub-)uJy level will enable us to detect radio emission from a large number of radio-quiet AGN at high redshift, providing a fundamental step in our understanding of their cosmological evolution. (Abridged) \\ ( http://arxiv.org/abs/1412.5846 , 52kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5884 Date: Thu, 18 Dec 2014 15:09:38 GMT (1917kb) Title: Unravelling lifecycles & physics of radio-loud AGN in the SKA era Authors: Anna D. Kapi\'nska, Martin J. Hardcastle, Carole A. Jackson, Tao An, Willem A. Baan, Matt J. Jarvis Categories: astro-ph.GA astro-ph.CO Comments: to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14), PoS(AASKA14)173 \\ Radio-loud AGN (>10^{22} W/Hz at 1.4 GHz) will be the dominant bright source population detected with the SKA. The high resolution that the SKA will provide even in wide-area surveys will mean that, for the first time sensitive, multi-frequency total intensity and polarisation imaging of large samples of radio-loud active galactic nuclei (AGN) will become available. The unprecedented sensitivity of the SKA coupled with its wide field of view capabilities will allow identification of objects of the same morphological type (i.e. the entire FR I, low- and high-luminosity FR II, disturbed morphology as well as weak radio-emitting AGN populations) up to high redshifts (z~4 and beyond), and at the same stage of their lives, from the youngest CSS/GPS sources to giant and fading (dying) sources, through to those with restarted activity radio galaxies and quasars. Critically, the wide frequency coverage of the SKA will permit analysis of same-epoch rest-frame radio properties, and the sensitivity and resolution will allow full cross-identification with multi-waveband data, further revealing insights into the physical processes driving the evolution of these radio sources. In this chapter of the SKA Science Book we give a summary of the main science drivers in the studies of lifecycles and detailed physics of radio-loud AGN, which include radio and kinetic luminosity functions, AGN feedback, radio-AGN triggering, radio-loud AGN unification and cosmological studies. We discuss the best parameters for the proposed SKA continuum surveys, both all-sky and deep field, in the light of these studies. \\ ( http://arxiv.org/abs/1412.5884 , 1917kb) ------------------------------------------------------------------------------ \\ arXiv:1412.6040 Date: Thu, 18 Dec 2014 20:01:39 GMT (90kb,D) Title: Identifying the first generation of radio powerful AGN in the Universe with the SKA Authors: Jose Afonso (1,2), Jordi Casanellas (3), Isabella Prandoni (4), Matt Jarvis (5,6), Silvio Lorenzoni (1), Manuela Magliocchetti (7), Nick Seymour (8) ((1) Institute of Astrophysics and Space Sciences, Portugal (2) Faculdade de Ciencias, Universidade de Lisboa (3) Max Planck Institut fur Gravitationsphysik (Albert-Einstein- Institut) (4) INAF - Istituto di Radioastronomia, Bologna (5) Astrophysics, University of Oxford (6) Physics Department, University of the Western Cape (7) INAF-IAPS (8) International Centre for Radio Astronomy Research, Curtin University) Categories: astro-ph.GA astro-ph.CO Comments: 10 pages, 2 figures. To appear as part of "Continuum Science" in the Proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)071 \\ One of the most challenging and exciting subjects in modern astrophysics is that of galaxy formation at the epoch of reionisation. The SKA, with its revolutionary capabilities in terms of frequency range, resolution and sensitivity, will allow to explore the first Gyr of structure formation in the Universe, in particular, with the detection and study of the earliest manifestations of the AGN phenomenon. The tens of QSOs that are currently known out to the highest redshifts (z~7), many of them exhibiting powerful radio emission, imply that super-massive black holes can be grown on a very short timescale and support the existence of very high redshift (z > 7) radio loud sources - sources that have so far escaped detection. Not only would such detections be paramount to the understanding of the earliest stages of galaxy evolution, they are necessary for the direct study of neutral hydrogen in the Epoch of Reionisation, through observations of the HI 21cm forest against such background sources. In order to understand how SKA and SKA1 observations can be optimised to reveal these earliest AGN, we have examined the effect of a hot CMB on the emission of powerful and young radio galaxies. By looking at the SKA1 capabilities, in particular in terms of wavelength coverage and resolution, we determine how the effects of "CMB-muting" of a radio loud source can be observationally minimised and how to identify the best highest-redshift radio candidates. Considering different predictions for the space density of radio loud AGN at such redshifts, we identify the survey characteristics necessary to optimize the detection and identification of the very first generation of radio loud AGN in the Universe. \\ ( http://arxiv.org/abs/1412.6040 , 90kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5971 Date: Thu, 18 Dec 2014 17:52:29 GMT (2430kb) Title: Very Long Baseline Interferometry with the SKA Authors: Zsolt Paragi, Leith Godfrey, Cormac Reynolds, Maria Rioja, Adam Deller, Bo Zhang, Leonid Gurvits, Michael Bietenholz, Arpad Szomoru, Hayley Bignall, Paul Boven, Patrick Charlot, Richard Dodson, Sandor Frey, Michael Garrett, Hiroshi Imai, Andrei Lobanov, Mark Reid, Eduardo Ros, Huib van Langevelde, J. Anton Zensus, Xing Wu Zheng, Antxon Alberdi, Ivan Agudo, Tao An, Megan Argo, Rob Beswick, Andy D. Biggs, Andreas Brunthaler, Robert M. Campbell, Giuseppe Cimo, Francisco Colomer, Stephane Corbel, John Conway, David Cseh, Roger Deane, Heino Falcke, Krisztina Gabanyi, Marcin Gawronski, Michael Gaylard, Gabriele Giovannini, Marcello Giroletti, Ciriaco Goddi, Sharmila Goedhart, Jose L. Gomez, Alastair Gunn, Taehyun Jung, Preeti Kharb, Hans-Rainer Klockner, Elmar Kording, Yurii Yu. Kovalev, Magdalena Kunert-Bajraszewska, Michael Lindqvist, Matt Lister, Franco Mantovani, Ivan Marti-Vidal, Mar Mezcua, John McKean, Enno Middelberg, James Miller-Jones, Javier Moldon, Tom Muxlow, Tim O'Brien, Miguel P\'erez-Torres, Sergei Pogrebenko, Jonathan Quick, Anthony P. Rushton, Richard Schilizzi, Oleg Smirnov, Bong Won Sohn, Gabriele Surcis, Greg Taylor, Steven Tingay, Valeriu Tudose, Alexander van der Horst, Joeri van Leeuwen, Tiziana Venturi, Rene Vermeulen, Wouter Vlemmings, Aletha de Witt, Olaf Wucknitz, Jun Yang Categories: astro-ph.IM astro-ph.CO astro-ph.GA astro-ph.HE astro-ph.SR Comments: 19 pages SKA-VLBI review paper with 5 figures, to be published in the proceedings of "Advancing Astrophysics with the Square Kilometre Array", PoS(AASKA14)143 \\ Adding VLBI capability to the SKA arrays will greatly broaden the science of the SKA, and is feasible within the current specifications. SKA-VLBI can be initially implemented by providing phased-array outputs for SKA1-MID and SKA1-SUR and using these extremely sensitive stations with other radio telescopes, and in SKA2 by realising a distributed configuration providing baselines up to thousands of km, merging it with existing VLBI networks. The motivation for and the possible realization of SKA-VLBI is described in this paper. \\ ( http://arxiv.org/abs/1412.5971 , 2430kb) ------------------------------------------------------------------------------ \\ arXiv:1412.5990 Date: Thu, 18 Dec 2014 18:40:10 GMT (4985kb,D) Title: Morphological classification of radio sources for galaxy evolution and cosmology with SKA-MID Authors: Sphesihle Makhathini, Oleg Smirnov, Matt Jarvis, Ian Heywood Categories: astro-ph.IM Comments: to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the Square Kilometre Array (AASKA14)' \\ Morphologically classifying radio sources in continuum images with the SKA has the potential to address some of the key questions in cosmology and galaxy evolution. In particular, we may use different classes of radio sources as independent tracers of the dark-matter density field, and thus overcome cosmic variance in measuring large-scale structure, while on the galaxy evolution side we could measure the mechanical feedback from FRII and FRI jets. This work makes use of a \texttt{MeqTrees}-based simulations framework to forecast the ability of the SKA to recover true source morphologies at high redshifts. A suite of high resolution images containing realistic continuum source distributions with different morphologies (FRI, FRII, starburst galaxies) is fed through an SKA Phase 1 simulator, then analysed to determine the sensitivity limits at which the morphologies can still be distinguished. We also explore how changing the antenna distribution affects these results. \\ ( http://arxiv.org/abs/1412.5990 , 4985kb) ------------------------------------------------------------------------------ \\ arXiv:1412.6076 Date: Thu, 18 Dec 2014 20:49:10 GMT (1002kb) Title: The SKA Mid-frequency All-sky Continuum Survey: Discovering the unexpected and transforming radio-astronomy Authors: Ray P. Norris, Kaustuv Basu, Michael Brown, Ettore Carretti, Anna D. Kapinska, Isabella Prandoni, Lawrence Rudnick, Nick Seymour Categories: astro-ph.IM Comments: to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)' \\ We show that, in addition to specific science goals, there is a strong case for conducting an all-sky (i.e. the visible 3-pi steradians) SKA continuum survey which does not fit neatly into conventional science cases. History shows that the greatest scientific impact of most major telescopes (e.g., HST, VLA) lies beyond the original goals used to justify the telescope. The design of the telescope therefore needs to maximise the ultimate scientific productivity, in addition to achieving the specific science goals. In this chapter, we show that an all-sky continuum survey is likely to achieve transformational science in two specific respects: (1) Discovering the unexpected (2) Transforming radio-astronomy from niche to mainstream \\ ( http://arxiv.org/abs/1412.6076 , 1002kb) ------------------------------------------------------------------------------ \\ arXiv:1412.6512 Date: Fri, 19 Dec 2014 20:15:11 GMT (528kb,D) Title: Revealing the Physics and Evolution of Galaxies and Galaxy Clusters with SKA Continuum Surveys Authors: I. Prandoni and N. Seymour (Continuum Science SKA Working Group) Categories: astro-ph.IM astro-ph.GA Comments: to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA' PoS(AASKA14)067. Overview chapter of the collection of 'Continuum Science' chapters \\ In this chapter we provide an overview of the science enabled by radio continuum surveys in the SKA era, focusing on galaxy/galaxy cluster physics and evolution studies, and other relevant continuum science in the >2020 scientific framework. We outline a number of 'reference' radio-continuum surveys for SKA1 that can address such topics, and comprehensively discuss the most critical science requirements that we have identified. We highlight what should be achieved by SKA1, to guarantee a major leap forwards with respect to the pre-SKA era, considering the science advances expected in the coming years with existing and upcoming telescopes (JVLA, LOFAR, eMERLIN, and the three SKA precursors: MWA, ASKAP and MeerKAT). In this exercise we take in due account also the other waveband facilities coming online at the same time (e.g. Euclid, LSST, etc.), which tackle overlapping scientific goals, but in a different manner. In this respect particular attention has been payed to ensure that the proposed reference surveys are able to exploit the existing synergies with such facilities, so as to generate strong involvement from all astronomical communities, and leave a lasting legacy value. It is clear that a certain degree of freedom is allowed to some of the observational parameters. We believe it is very important to best fine-tune such parameters taking into proper account existing commensalities with SKA1 surveys addressing other science areas (HI galaxy science, magnetism, cosmology). \\ ( http://arxiv.org/abs/1412.6512 , 528kb) ------------------------------------------------------------------------------ \\ arXiv:1412.6481 (*cross-listing*) Date: Fri, 19 Dec 2014 18:44:57 GMT (347kb) Title: Tomography of Galactic star-forming regions and spiral arms with the Square Kilometer Array Authors: Laurent Loinard (CRyA-UNAM), Mark Thompson (University of Hertfordshire), Melvin Hoare (Leeds University), Huib Jan van Langevelde (JIVE/Sterrewacht Leiden), Simon Ellingsen (University of Tasmania), Andreas Brunthaler (MPIfR Bonn), Jan Forbrich (University of Vienna), Kazi L.J. Rygl (ESA-ESTEC Noordwijk), Luis F. Rodriguez (CRyA-UNAM), Amy J. Mioduszewski (NRAO Socorro), Rosa M. Torres-Lopez (U. Guadalajara), Sergio A. Dzib (MPIfR Bonn), Gisela N. Ortiz-Leon (CRyA-UNAM), Tyler L. Bourke (SKA Organisation), James A. Green (SKA Organisation) Categories: astro-ph.SR astro-ph.GA Comments: To appear in the Proceedings Advancing Astrophysics with the SKA (AASKA14) \\ Very Long Baseline Interferometry (VLBI) at radio wavelengths can provide astrometry accurate to 10 micro-arcseconds or better (i.e. better than the target GAIA accuracy) without being limited by dust obscuration. This means that unlike GAIA, VLBI can be applied to star-forming regions independently of their internal and line-of-sight extinction. Low-mass young stellar objects (particularly T Tauri stars) are often non-thermal compact radio emitters, ideal for astrometric VLBI radio continuum experiments. Existing observations for nearby regions (e.g. Taurus, Ophiuchus, or Orion) demonstrate that VLBI astrometry of such active T Tauri stars enables the reconstruction of both the regions' 3D structure (through parallax measurements) and their internal kinematics (through proper motions, combined with radial velocities). The extraordinary sensitivity of the SKA telescope will enable similar "tomographic mappings" to be extended to regions located several kpc from Earth, in particular to nearby spiral arm segments. This will have important implications for Galactic science, galactic dynamics and spiral structure theories. \\ ( http://arxiv.org/abs/1412.6481 , 347kb) ------------------------------------------------------------------------------ \\ arXiv:1412.6409 (*cross-listing*) Date: Fri, 19 Dec 2014 16:05:16 GMT (1306kb,D) Title: Radio Jets in Young Stellar Objects with the SKA Authors: Guillem Anglada, Luis F. Rodriguez and Carlos Carrasco-Gonzalez Categories: astro-ph.SR astro-ph.IM Comments: 8 pages, 3 figures, to be published in proceedings of "Advancing Astrophysics with the Square Kilometre Array", PoS(AASKA14)121 \\ Jets are ubiquitous in the star-forming process since accretion is intimately associated with outflow. Weak free-free continuum emission in the centimeter domain is associated with these jets. Observations in the cm range are most useful to trace the base of the ionized jets, close to the YSO and its accretion disk, where jets are accelerated and collimated. Optical or near-IR images are obscured by the high extinction present. Radio recombination lines in jets (in combination with proper motions) should provide their 3D kinematics. SKA will be crucial to perform this kind of observations. Thermal radio jets are associated with both low and high mass protostars. The ionizing mechanism appears to be related to shocks in the associated outflows, as suggested by the observed correlation between the centimeter luminosity and the outflow momentum rate. From this correlation and that with the bolometric luminosity of the driving star it will be possible to discriminate with SKA between unresolved HII regions and jets, and to infer physical properties of the embedded objects. Some jets show indications of non-thermal emission (negative spectral indices) in their lobes. Linearly polarized synchrotron emission has been found in the lobes of the jet of HH 80-81, allowing us to measure the direction and intensity of the magnetic field, a clue ingredient in determining the jet collimation and ejection mechanisms. As only a fraction of the emission is polarized, very sensitive observations such as those that will be feasible with SKA are required to perform these studies in other objects. Jets are common in many kinds of astrophysical scenarios. Characterizing YSO radio jets, whose physical conditions can be reliably determined from their thermal emission, would be also useful in understanding acceleration and collimation mechanisms in all kinds of astrophysical jets. \\ ( http://arxiv.org/abs/1412.6409 , 1306kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00315 Date: Thu, 1 Jan 2015 21:00:11 GMT (3274kb) Title: Filaments of the radio cosmic web: opportunities and challenges for SKA Authors: Franco Vazza, Chiara Ferrari, Annalisa Bonafede, Marcus Br\"{u}ggen, Claudio Gheller, Robert Braun and Shea Brown Categories: astro-ph.CO Comments: 10 pages, 4 figures, to appear in Proceedings of 'Advancing Astrophysics with the SKA (AASKA14) - Cosmic Magnetism' Chapters \\ The detection of the diffuse gas component of the cosmic web remains a formidable challenge. In this work we study synchrotron emission from the cosmic web with simulated SKA1 observations, which can represent an fundamental probe of the warm-hot intergalactic medium. We investigate radio emission originated by relativistic electrons accelerated by shocks surrounding cosmic filaments, assuming diffusive shock acceleration and as a function of the (unknown) large-scale magnetic fields. The detection of the brightest parts of large ($>10 \rm Mpc$) filaments of the cosmic web should be within reach of the SKA1-LOW, if the magnetic field is at the level of a $\sim 10$ percent equipartition with the thermal gas, corresponding to $\sim 0.1 \mu G$ for the most massive filaments in simulations. In the course of a 2-years survey with SKA1-LOW, this will enable a first detection of the "tip of the iceberg" of the radio cosmic web, and allow for the use of the SKA as a powerful tool to study the origin of cosmic magnetism in large-scale structures. On the other hand, the SKA1-MID and SKA1-SUR seem less suited for this science case at low redshift ($z \leq 0.4$), owing to the missing short baselines and the consequent lack of signal from the large-scale brightness fluctuations associated with the filaments. In this case only very long exposures ($\sim 1000$ hr) may enable the detection of $\sim 1-2$ filament for field of view in the SKA1-SUR PAF Band1. \\ ( http://arxiv.org/abs/1501.00315 , 3274kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00321 Date: Thu, 1 Jan 2015 21:53:43 GMT (594kb) Title: Unravelling the origin of large-scale magnetic fields in galaxy clusters and beyond through Faraday Rotation Measures with the SKA Authors: A. Bonafede, F. Vazza, M.Br\"uggen, T. Akahori, E. Carretti, S. Colafrancesco, L. Feretti, C. Ferrari, G. Giovannini, F. Govoni, M. Johnston-Hollitt, M. Murgia, L. Rudnick, A. Scaife, V. Vacca Categories: astro-ph.CO astro-ph.HE astro-ph.IM Comments: 9 pages, 4 Figures, to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14) \\ We investigate the possibility for the SKA to detect and study the magnetic fields in galaxy clusters and in the less dense environments surrounding them using Faraday Rotation Measures. To this end, we produce 3-dimensional magnetic field models for galaxy clusters of different masses and in different stages of their evolution, and derive mock rotation measure observations of background radiogalaxies. According to our results, already in phase I, we will be able to infer the magnetic field properties in galaxy clusters as a function of the cluster mass, down to $10^{13}$ solar-masses. Moreover, using cosmological simulations to model the gas density, we have computed the expected rotation measure through shock-fronts that occur in the intra-cluster medium during cluster mergers. The enhancement in the rotation measure due to the density jump will permit to constraint the magnetic field strength and structure after the shock passage. SKA observations of polarised sources located behind galaxy clusters will answer several questions about the magnetic field strength and structure in galaxy clusters, and its evolution with cosmic time. \\ ( http://arxiv.org/abs/1501.00321 , 594kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00389 Date: Fri, 2 Jan 2015 11:43:59 GMT (2000kb) Title: Cluster magnetic fields through the study of polarized radio halos in the SKA era Authors: F. Govoni, M. Murgia, H. Xu, H. Li, M. Norman, L. Feretti, G. Giovannini, V. Vacca, G. Bernardi, A. Bonafede, G. Brunetti, E. Carretti, S. Colafrancesco, J. Donnert, C. Ferrari, M. Gitti, L. Iapichino, M. Johnston-Hollitt, R. Pizzo, L. Rudnick Categories: astro-ph.CO Comments: 11 pages, 4 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)105 \\ Galaxy clusters are unique laboratories to investigate turbulent fluid motions and large scale magnetic fields. Synchrotron radio halos at the center of merging galaxy clusters provide the most spectacular and direct evidence of the presence of relativistic particles and magnetic fields associated with the intracluster medium. The study of polarized emission from radio halos is extremely important to constrain the properties of intracluster magnetic fields and the physics of the acceleration and transport of the relativistic particles. However, detecting this polarized signal is a very hard task with the current radio facilities.We use cosmological magneto-hydrodynamical simulations to predict the expected polarized surface brightness of radio halos at 1.4 GHz. We compare these expectations with the sensitivity and the resolution reachable with the SKA1. This allows us to evaluate the potential for studying intracluster magnetic fields in the surveys planned for SKA1. \\ ( http://arxiv.org/abs/1501.00389 , 2000kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00415 Date: Fri, 2 Jan 2015 14:43:51 GMT (54kb) Title: Statistical methods for the analysis of rotation measure grids in large scale structures in the SKA era Authors: Valentina Vacca, Niels Oppermann, Torsten Ensslin, Marco Selig, Henrik Junklewitz, Maksim Greiner, Jens Jasche, Christopher Hales, Martin Reinecke, Ettore Carretti, Luigina Feretti, Chiara Ferrari, Gabriele Giovannini, Federica Govoni, Cathy Horellou, Shinsuke Ideguchi, Melanie Johnston-Hollitt, Matteo Murgia, Rosita Paladino, Roberto Francesco Pizzo, Scaife Anna Categories: astro-ph.CO Comments: 9 pages; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)114 \\ To better understand the origin and properties of cosmological magnetic fields, a detailed knowledge of magnetic fields in the large-scale structure of the Universe (galaxy clusters, filaments) is crucial. We propose a new statistical approach to study magnetic fields on large scales with the rotation measure grid data that will be obtained with the new generation of radio interferometers. \\ ( http://arxiv.org/abs/1501.00415 , 54kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00385 Date: Fri, 2 Jan 2015 11:27:00 GMT (557kb) Title: Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era Authors: Rainer Beck, Dominik Bomans, Sergio Colafrancesco, Ralf-J\"urgen Dettmar, Katia Ferri\`ere, Andrew Fletcher, George Heald, Volker Heesen, Cathy Horellou, Marita Krause, Yu-Qing Lou, Sui Ann Mao, Rosita Paladino, Eva Schinnerer, Dmitry Sokoloff, Jeroen Stil and Fatemeh Tabatabaei Categories: astro-ph.GA Comments: 18 pages, 3 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA' (AASKA14) as article PoS(AASKA14)094 MSC-class: 85-06 Journal-ref: Proceedings of Science, PoS(AASKA14)094, 2015 \\ Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which in turn are pivotal in shaping the structure of halo magnetic fields. Mapping the small-scale structure of interstellar magnetic fields in many nearby galaxies is crucial to understand the interaction between gas and magnetic fields, in particular how gas flows are affected. Elucidation of the magnetic role in, e.g., triggering star formation, forming and stabilising spiral arms, driving outflows, gas heating by reconnection and magnetising the intergalactic medium has the potential to revolutionise our physical picture of the ISM and galaxy evolution in general. Radio polarisation observations in the very nearest galaxies at high frequencies (>= 3 GHz) and with high spatial resolution (<= 5") hold the key here. The galaxy survey with SKA1 that we propose will also be a major step to understand the galactic dynamo, which is important for models of galaxy evolution and for astrophysical magnetohydrodynamics in general. Field amplification by turbulent gas motions, which is crucial for efficient dynamo action, has been investigated so far only in simulations, while compelling evidence of turbulent fields from observations is still lacking. \\ ( http://arxiv.org/abs/1501.00385 , 557kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00407 Date: Fri, 2 Jan 2015 14:12:51 GMT (212kb) Title: Giant radio galaxies as probes of the ambient WHIM in the era of the SKA Authors: Bo Peng, Ru-Rong Chen and Richard Strom Categories: astro-ph.GA Comments: 8 pages, 3 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14) \\ The missing baryons are usually thought to reside in galaxy filaments as warm-hot intergalactic medium (WHIM). From previous studies, giant radio galaxies are usually associated with galaxy groups, which normally trace the WHIM. We propose observations with the powerful SKA1 to make a census of giant radio galaxies in the southern hemisphere, which will probe the ambient WHIM. The radio galaxies discovered will also be investigated to search for dying radio sources. With the highly improved sensitivity and resolution of SKA1, more than 6,000 giant radio sources will be discovered within 250 hours. \\ ( http://arxiv.org/abs/1501.00407 , 212kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00408 Date: Fri, 2 Jan 2015 14:13:20 GMT (592kb,D) Title: Magnetic Field Tomography in Nearby Galaxies with the Square Kilometre Array Authors: George Heald, Rainer Beck, W.J.G. de Blok, Ralf-Juergen Dettmar, Andrew Fletcher, Bryan Gaensler, Marijke Haverkorn, Volker Heesen, Cathy Horellou, Marita Krause, Sui Ann Mao, Niels Oppermann, Anna Scaife, Dmitry Sokoloff, Jeroen Stil, Fatemeh Tabatabaei, Keitaro Takahashi, Russ Taylor and Anna Williams Categories: astro-ph.GA Comments: 11 pages, 1 figure; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)106 \\ Magnetic fields play an important role in shaping the structure and evolution of the interstellar medium (ISM) of galaxies, but the details of this relationship remain unclear. With SKA1, the 3D structure of galactic magnetic fields and its connection to star formation will be revealed. A highly sensitive probe of the internal structure of the magnetoionized ISM is the partial depolarization of synchrotron radiation from inside the volume. Different configurations of magnetic field and ionized gas within the resolution element of the telescope lead to frequency-dependent changes in the observed degree of polarization. The results of spectro-polarimetric observations are tied to physical structure in the ISM through comparison with detailed modeling, supplemented with the use of new analysis techniques that are being actively developed and studied within the community such as Rotation Measure Synthesis. The SKA will enable this field to come into its own and begin the study of the detailed structure of the magnetized ISM in a sample of nearby galaxies, thanks to its extraordinary wideband capabilities coupled with the combination of excellent surface brightness sensitivity and angular resolution. \\ ( http://arxiv.org/abs/1501.00408 , 592kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00416 Date: Fri, 2 Jan 2015 14:48:12 GMT (1897kb,D) Title: Measuring magnetism in the Milky Way with the Square Kilometre Array Authors: Marijke Haverkorn, Takuya Akahori, Ettore Carretti, Katia Ferriere, Peter Frick, Bryan Gaensler, George Heald, Melanie Johnston-Hollitt, David Jones, Tom Landecker, Sui Ann Mao, Aris Noutsos, Niels Oppermann, Wolfgang Reich, Timothy Robishaw, Anna Scaife, Dominic Schnitzeler, Rodion Stepanov, Xiaohui Sun, Russ Taylor, for the SKA Cosmic Magnetism Working Group Categories: astro-ph.GA Comments: 19 pages, 2 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)096 \\ Magnetic fields in the Milky Way are present on a wide variety of sizes and strengths, influencing many processes in the Galactic ecosystem such as star formation, gas dynamics, jets, and evolution of supernova remnants or pulsar wind nebulae. Observation methods are complex and indirect; the most used of these are a grid of rotation measures of unresolved polarized extragalactic sources, and broadband polarimetry of diffuse emission. Current studies of magnetic fields in the Milky Way reveal a global spiral magnetic field with a significant turbulent component; the limited sample of magnetic field measurements in discrete objects such as supernova remnants and HII regions shows a wide variety in field configurations; a few detections of magnetic fields in Young Stellar Object jets have been published; and the magnetic field structure in the Galactic Center is still under debate. The SKA will unravel the 3D structure and configurations of magnetic fields in the Milky Way on sub-parsec to galaxy scales, including field structure in the Galactic Center. The global configuration of the Milky Way disk magnetic field, probed through pulsar RMs, will resolve controversy about reversals in the Galactic plane. Characteristics of interstellar turbulence can be determined from the grid of background RMs. We expect to learn to understand magnetic field structures in protostellar jets, supernova remnants, and other discrete sources, due to the vast increase in sample sizes possible with the SKA. This knowledge of magnetic fields in the Milky Way will not only be crucial in understanding of the evolution and interaction of Galactic structures, but will also help to define and remove Galactic foregrounds for a multitude of extragalactic and cosmological studies. \\ ( http://arxiv.org/abs/1501.00416 , 1897kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00420 Date: Fri, 2 Jan 2015 15:03:23 GMT (1276kb) Title: Studies of Relativistic Jets in Active Galactic Nuclei with SKA Authors: Ivan Agudo, Markus Boettcher, Heino Falcke, Markos Georganopoulos, Gabriele Ghisellini, Gabriele Giovannini, Marcello Giroletti, Jose L. Gomez, Leonid Gurvits, Robert Laing, Matthew Lister, Jose-Maria Marti, Eileen T. Meyer, Yosuke Mizuno, Shane O'Sullivan, Paolo Padovani, Zsolt Paragi, Manel Perucho, Dominik Schleicher, Lukasz Stawarz, Nektarios Vlahakis and John Wardle Categories: astro-ph.GA astro-ph.CO astro-ph.HE astro-ph.IM Comments: 19 pages, 4 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14_093) \\ Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. These questions will be addressed specially through analysis of the massive data sets arising from the deep, all-sky surveys (both total and polarimetric flux) from SKA1. Wide-field very-long-baseline-interferometric survey observations involving SKA1 will serve as a unique tool for distinguishing between extragalactic relativistic jets and star forming galaxies via brightness temperature measurements. Subsequent SKA1 studies of relativistic jets at different resolutions will allow for unprecedented cosmological studies of AGN jets up to the epoch of re-ionization, enabling detailed characterization of the jet composition, magnetic field, particle populations, and plasma properties on all scales. SKA will enable us to study the dependence of jet power and star formation on other properties of the AGN system. SKA1 will enable such studies for large samples of jets, while VLBI observations involving SKA1 will provide the sensitivity for pc-scale imaging, and SKA2 (with its extraordinary sensitivity and dynamic range) will allow us for the first time to resolve and model the weakest radio structures in the most powerful radio-loud AGN. \\ ( http://arxiv.org/abs/1501.00420 , 1276kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00452 Date: Fri, 2 Jan 2015 18:11:58 GMT (1436kb) Title: Kinematics and Dynamics of kiloparsec-scale Jets in Radio Galaxies with SKA Authors: R. A. Laing (ESO) Categories: astro-ph.GA astro-ph.HE Comments: 9 pages. 3 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14) \\ We explore the use of SKA to deduce the physical parameters of kiloparsec-scale jet flows in radio galaxies. Jets in Active Galactic Nuclei are relativistic where they are first formed, but their speeds and compositions change as they propagate. It has long been known that kiloparsec-scale jets in radio galaxies can be divided into two flavours: strong (found in powerful sources, narrow and terminating in compact hot-spots) and weak (found in low-luminosity sources, geometrically flaring, unable to form hot-spots and terminating in diffuse lobes or tails). We have developed methods to model AGN jets as intrinsically symmetrical, relativistic flows by fitting to deep, well-resolved radio images in Stokes I, Q and U. This has yielded a wealth of information about the brightest few weak-flavour jets. Our first key objective is to observe large samples of weak and transition jets at 0.1 - 0.5 arcsec resolution with SKA1-MID. This would allow us to see how jet propagation depends on power and environment and to quantify the energy and momentum input into the IGM. We will require typical noise levels of 1 microJy/beam, and may be able to exploit survey imaging in some cases. Our second, more challenging, application is to determine the velocity fields in strong-flavour jets. Do they have very fast spines with bulk Lorentz factors of 5 - 10? Is there evidence for magnetic confinement by a toroidal field? What are their energy fluxes? This is a major imaging challenge for SKA2: we need resolution better than 0.05 arcsec, ideally in the 1 - 10 GHz frequency range, with rms noise levels of roughly 10 nJy/beam and extremely high dynamic range, imaging fidelity and polarization purity. \\ ( http://arxiv.org/abs/1501.00452 , 1436kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00056 Date: Wed, 31 Dec 2014 00:49:25 GMT (1417kb,D) Title: A Cosmic Census of Radio Pulsars with the SKA Authors: E. F. Keane, B. Bhattacharyya, M. Kramer, B. W. Stappers, S. D. Bates, M. Burgay, S. Chatterjee, D. J. Champion, R. P. Eatough, J. W. T. Hessels, G. Janssen, K. J. Lee, J. van Leeuwen, J. Margueron, M. Oertel, A. Possenti, S. Ransom, G. Theureau, P. Torne Categories: astro-ph.IM astro-ph.HE astro-ph.SR Comments: 20 pages, 7 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)040 \\ The Square Kilometre Array (SKA) will make ground breaking discoveries in pulsar science. In this chapter we outline the SKA surveys for new pulsars, as well as how we will perform the necessary follow-up timing observations. The SKA's wide field-of-view, high sensitivity, multi-beaming and sub-arraying capabilities, coupled with advanced pulsar search backends, will result in the discovery of a large population of pulsars. These will enable the SKA's pulsar science goals (tests of General Relativity with pulsar binary systems, investigating black hole theorems with pulsar-black hole binaries, and direct detection of gravitational waves in a pulsar timing array). Using SKA1-MID and SKA1-LOW we will survey the Milky Way to unprecedented depth, increasing the number of known pulsars by more than an order of magnitude. SKA2 will potentially find all the Galactic radio-emitting pulsars in the SKA sky which are beamed in our direction. This will give a clear picture of the birth properties of pulsars and of the gravitational potential, magnetic field structure and interstellar matter content of the Galaxy. Targeted searches will enable detection of exotic systems, such as the ~1000 pulsars we infer to be closely orbiting Sgr A*, the supermassive black hole in the Galactic Centre. In addition, the SKA's sensitivity will be sufficient to detect pulsars in local group galaxies. To derive the spin characteristics of the discoveries we will perform live searches, and use sub-arraying and dynamic scheduling to time pulsars as soon as they are discovered, while simultaneously continuing survey observations. The large projected number of discoveries suggests that we will uncover currently unknown rare systems that can be exploited to push the boundaries of our understanding of astrophysics and provide tools for testing physics, as has been done by the pulsar community in the past. \\ ( http://arxiv.org/abs/1501.00056 , 1417kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00127 Date: Wed, 31 Dec 2014 12:53:40 GMT (1247kb) Title: Gravitational wave astronomy with the SKA Authors: G.H. Janssen (ASTRON), G. Hobbs (CSIRO), M. McLaughlin (WVU), C.G. Bassa (ASTRON), A.T. Deller (ASTRON), M. Kramer (MPIfR Bonn/Manchester), K.J. Lee (Peking University/MPIfR Bonn), C.M.F. Mingarelli (MPIfR Bonn, CalTech, University of Birmingham), P.A. Rosado (AEI Hanover/Swinburne), S. Sanidas (Manchester), A. Sesana (AEI Golm), L. Shao (Peking University), I.H. Stairs (UBC), B.W. Stappers (Manchester), J.P.W. Verbiest (Bielefeld/MPIfR Bonn) Categories: astro-ph.IM astro-ph.HE Comments: 19 pages, 3 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)037 \\ On a time scale of years to decades, gravitational wave (GW) astronomy will become a reality. Low frequency (nanoHz) GWs are detectable through long-term timing observations of the most stable pulsars. Radio observatories worldwide are currently carrying out observing programmes to detect GWs, with data sets being shared through the International Pulsar Timing Array project. One of the most likely sources of low frequency GWs are supermassive black hole binaries (SMBHBs), detectable as a background due to a large number of binaries, or as continuous or burst emission from individual sources. No GW signal has yet been detected, but stringent constraints are already being placed on galaxy evolution models. The SKA will bring this research to fruition. In this chapter, we describe how timing observations using SKA1 will contribute to detecting GWs, or can confirm a detection if a first signal already has been identified when SKA1 commences observations. We describe how SKA observations will identify the source(s) of a GW signal, search for anisotropies in the background, improve models of galaxy evolution, test theories of gravity, and characterise the early inspiral phase of a SMBHB system. We describe the impact of the large number of millisecond pulsars to be discovered by the SKA; and the observing cadence, observation durations, and instrumentation required to reach the necessary sensitivity. We describe the noise processes that will influence the achievable precision with the SKA. We assume a long-term timing programme using the SKA1-MID array and consider the implications of modifications to the current design. We describe the possible benefits from observations using SKA1-LOW. Finally, we describe GW detection prospects with SKA1 and SKA2, and end with a description of the expectations of GW astronomy. \\ ( http://arxiv.org/abs/1501.00127 , 1247kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00281 Date: Thu, 1 Jan 2015 14:13:41 GMT (1633kb) Title: Observing Radio Pulsars in the Galactic Centre with the Square Kilometre Array Authors: R. P. Eatough, T. J. W. Lazio, J. Casanellas, S. Chatterjee, J. M. Cordes, P. B. Demorest, M. Kramer, K. J. Lee, K. Liu, S. M. Ransom, N. Wex Categories: astro-ph.IM astro-ph.GA astro-ph.HE Comments: 14 pages, 5 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)045 \\ The discovery and timing of radio pulsars within the Galactic centre is a fundamental aspect of the SKA Science Case, responding to the topic of "Strong Field Tests of Gravity with Pulsars and Black Holes" (Kramer et al. 2004; Cordes et al. 2004). Pulsars have in many ways proven to be excellent tools for testing the General theory of Relativity and alternative gravity theories (see Wex (2014) for a recent review). Timing a pulsar in orbit around a companion, provides a unique way of probing the relativistic dynamics and spacetime of such a system. The strictest tests of gravity, in strong field conditions, are expected to come from a pulsar orbiting a black hole. In this sense, a pulsar in a close orbit ($P_{\rm orb}$ < 1 yr) around our nearest supermassive black hole candidate, Sagittarius A* - at a distance of ~8.3 kpc in the Galactic centre (Gillessen et al. 2009a) - would be the ideal tool. Given the size of the orbit and the relativistic effects associated with it, even a slowly spinning pulsar would allow the black hole spacetime to be explored in great detail (Liu et al. 2012). For example, measurement of the frame dragging caused by the rotation of the supermassive black hole, would allow a test of the "cosmic censorship conjecture." The "no-hair theorem" can be tested by measuring the quadrupole moment of the black hole. These are two of the prime examples for the fundamental studies of gravity one could do with a pulsar around Sagittarius A*. As will be shown here, SKA1-MID and ultimately the SKA will provide the opportunity to begin to find and time the pulsars in this extreme environment. \\ ( http://arxiv.org/abs/1501.00281 , 1633kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00390 Date: Fri, 2 Jan 2015 12:23:05 GMT (745kb) Title: Stacking for Cosmic Magnetism with SKA Surveys Authors: J. M. Stil, B. W. Keller Categories: astro-ph.IM astro-ph.GA Comments: 9 pages, 3 figures (figure 3 in two parts). To appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)112 \\ Stacking polarized radio emission in SKA surveys provides statistical information on large samples that is not accessible otherwise due to limitations in sensitivity, source statistics in small fields, and averaging over frequency (including Faraday synthesis). Polarization is a special case because one obvious source of stacking targets is the Stokes I source catalog, possibly in combination with external catalogs, for example an SKA HI survey or a non-radio survey. We point out the significance of stacking sub-samples selected by additional observable parameters to investigate relations that reveal more about the physics of the source. Applications of stacking polarization include, but are not limited to, obtaining in a statistical sense polarization information to the detection limit in total intensity, depolarization as a function of cosmic time at consistent source-frame wavelengths, magnetic field properties in objects with a low radio luminosity such as dwarf and low-surface-brightness galaxies, and investigating potential correlations of observable parameters with the average magnetic field direction in a sample. We also point out the potential use of stacking in validating the polarization calibration of a survey. While stacking is flexible in terms of survey definition, we discuss optimal survey parameters for the science experiments presented, as well as computing and archiving requirements. \\ ( http://arxiv.org/abs/1501.00390 , 745kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00042 (*cross-listing*) Date: Tue, 30 Dec 2014 23:03:48 GMT (2706kb,D) Title: Probing the neutron star interior and the Equation of State of cold dense matter with the SKA Authors: Anna Watts, Renxin Xu, Cristobal Espinoza, Nils Andersson, John Antoniadis, Danai Antonopoulou, Sarah Buchner, Shi Dai, Paul Demorest, Paulo Freire, Jason Hessels, Jerome Margueron, Micaela Oertel, Alessandro Patruno, Andrea Possenti, Scott Ransom, Ingrid Stairs, Ben Stappers Categories: astro-ph.SR astro-ph.HE astro-ph.IM nucl-th Comments: 22 pages, 8 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)043 \\ With an average density higher than the nuclear density, neutron stars (NS) provide a unique test-ground for nuclear physics, quantum chromodynamics (QCD), and nuclear superfluidity. Determination of the fundamental interactions that govern matter under such extreme conditions is one of the major unsolved problems of modern physics, and -- since it is impossible to replicate these conditions on Earth -- a major scientific motivation for SKA. The most stringent observational constraints come from measurements of NS bulk properties: each model for the microscopic behaviour of matter predicts a specific density-pressure relation (its `Equation of state', EOS). This generates a unique mass-radius relation which predicts a characteristic radius for a large range of masses and a maximum mass above which NS collapse to black holes. It also uniquely predicts other bulk quantities, like maximum spin frequency and moment of inertia. The SKA, in Phase 1 and particularly in Phase 2 will, thanks to the exquisite timing precision enabled by its raw sensitivity, and surveys that dramatically increase the number of sources: 1) Provide many more precise NS mass measurements (high mass NS measurements are particularly important for ruling out EOS models); 2) Allow the measurement of the NS moment of inertia in highly relativistic binaries such as the Double Pulsar; 3) Greatly increase the number of fast-spinning NS, with the potential discovery of spin frequencies above those allowed by some EOS models; 4) Improve our knowledge of new classes of binary pulsars such as black widows and redbacks (which may be massive as a class) through sensitive broad-band radio observations; and 5) Improve our understanding of dense matter superfluidity and the state of matter in the interior through the study of rotational glitches, provided that an ad-hoc campaign is developed. \\ ( http://arxiv.org/abs/1501.00042 , 2706kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00058 (*cross-listing*) Date: Wed, 31 Dec 2014 00:53:46 GMT (473kb,D) Title: Testing Gravity with Pulsars in the SKA Era Authors: Lijing Shao, Ingrid H. Stairs, John Antoniadis, Adam T. Deller, Paulo C. C. Freire, Jason W. T. Hessels, Gemma H. Janssen, Michael Kramer, Jutta Kunz, Claus L\"ammerzahl, Volker Perlick, Andrea Possenti, Scott Ransom, Benjamin W. Stappers, Willem van Straten Categories: astro-ph.HE astro-ph.IM astro-ph.SR gr-qc Comments: 20 pages, 4 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)042 \\ The Square Kilometre Array (SKA) will use pulsars to enable precise measurements of strong gravity effects in pulsar systems, which yield tests of gravitational theories that cannot be carried out anywhere else. The Galactic census of pulsars will discover dozens of relativistic pulsar systems, possibly including pulsar -- black hole binaries which can be used to test the "cosmic censorship conjecture" and the "no-hair theorem". Also, the SKA's remarkable sensitivity will vastly improve the timing precision of millisecond pulsars, allowing probes of potential deviations from general relativity (GR). Aspects of gravitation to be explored include tests of strong equivalence principles, gravitational dipole radiation, extra field components of gravitation, gravitomagnetism, and spacetime symmetries. \\ ( http://arxiv.org/abs/1501.00058 , 473kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00749 Date: Mon, 5 Jan 2015 02:44:14 GMT (581kb) Title: Topology of neutral hydrogen distribution with the Square Kilometer Array Authors: Yougang Wang, Yidong Xu, Fengquan Wu, Xuelei Chen, Xin Wang, Juhan Kim, Changbom Park, Khee-Gan Lee, Renyue Cen Categories: astro-ph.CO Comments: 11 pages, 5 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)033 \\ Morphology of the complex HI gas distribution can be quantified by statistics like the Minkowski functionals, and can provide a way to statistically study the large scale structure in the HI maps both at low redshifts, and during the epoch of reionization (EoR). At low redshifts, the 21cm emission traces the underlying matter distribution. Topology of the HI gas distribution, as measured by the genus, could be used as a "standard ruler". This enables the determination of distance-redshift relation and also the discrimination of various models of dark energy and of modified gravity. The topological analysis is also sensitive to certain primordial non-Gaussian features. Compared with two-point statistics, the topological statistics are more robust against the nonlinear gravitational evolution, bias, and redshift-space distortion. The HI intensity map observation naturally avoids the sparse sampling distortion, which is an important systematic in optical galaxy survey. The large cosmic volume accessible to SKA would provide unprecedented accuracy using such a measurement... [abridged] \\ ( http://arxiv.org/abs/1501.00749 , 581kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00761 Date: Mon, 5 Jan 2015 04:54:09 GMT (6572kb,D) Title: Using Tailed Radio Galaxies to Probe the Environment and Magnetic Field of Galaxy Clusters in the SKA Era Authors: M. Johnston-Hollitt, S. Dehghan, L. Pratley Categories: astro-ph.GA Comments: 9 pages, 2 figures, to appear in proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)101 \\ The morphology of tailed radio galaxies is an invaluable source of environmental information, in which a history of the past interactions in the intra-cluster medium, such as complex galaxy motions and cluster merger shocks, are preserved. In recent years, the use of tailed radio galaxies as environmental probes has gained momentum as a method for galaxy cluster detection, examining the dynamics of individual clusters, measuring the density and velocity flows in the intra-cluster medium, and for probing cluster magnetic fields. To date instrumental limitations in terms of resolution and sensitivity have confined this research to the local (z < 0.7) Universe. The advent of SKA1 surveys however will allow detection of roughly 1,000,000 tailed radio galaxies and their associated galaxy clusters out to redshifts of 2 or more. This is in fact ten times more than the current number of known clusters in the Universe. Additionally between 50,000 and 100,000 tailed radio galaxies will be sufficiently polarized to allow characterization of the magnetic field of their parent cluster. Such a substantial sample of tailed galaxies will provide an invaluable tool not only for detecting clusters, but also for characterizing their intra-cluster medium, magnetic fields and dynamical state as a function of cosmic time. In this chapter we present an analysis of the usability of tailed radio galaxies as tracers of dense environments extrapolated from existing deep radio surveys. \\ ( http://arxiv.org/abs/1501.00761 , 6572kb) ------------------------------------------------------------------------------ \\ arXiv:1501.00804 Date: Mon, 5 Jan 2015 10:00:29 GMT (169kb,D) Title: SKA studies of in-situ synchrotron radiation from molecular clouds Authors: Clive Dickinson, R. Beck, R. Crocker, R.M. Crutcher, R.D. Davies, K. Ferriere, G. Fuller, T. Jaffe, D.I. Jones, J.P. Leahy, E.J. Murphy, M.W. Peel, E. Orlando, T. Porter, R.J. Protheroe, T. Robishaw, A.W. Strong, R.A. Watson, F. Yusef-Zadeh Categories: astro-ph.GA Comments: 10 pages, 1 figure, as part of "Cosmic Magnetism" in Proceedings "Advancing Astrophysics with the SKA (AASKA14)", PoS(AASKA14)102 \\ Observations of the properties of dense molecular clouds are critical in understanding the process of star-formation. One of the most important, but least understood, is the role of the magnetic fields. We discuss the possibility of using high-resolution, high-sensitivity radio observations with the SKA to measure for the first time the in-situ synchrotron radiation from these molecular clouds. If the cosmic-ray (CR) particles penetrate clouds as expected, then we can measure the B-field strength directly using radio data. So far, this signature has never been detected from the collapsing clouds themselves and would be a unique probe of the magnetic field. Dense cores are typically ~0.05 pc in size, corresponding to ~arcsec at ~kpc distances, and flux density estimates are ~mJy at 1 GHz. The SKA should be able to readily detect directly, for the first time, along lines-of-sight that are not contaminated by thermal emission or complex foreground/background synchrotron emission. Polarised synchrotron may also be detectable providing additional information about the regular/turbulent fields. \\ ( http://arxiv.org/abs/1501.00804 , 169kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01023 Date: Fri, 2 Jan 2015 11:20:55 GMT (1044kb) Title: Mega-parsec scale magnetic fields in low density regions in the SKA era: filaments connecting galaxy clusters and groups Authors: Gabriele Giovannini, Annalisa Bonafede, Shea Brown, Luigina Feretti, Chiara Ferrari, Myriam Gitti, Federica Govoni, Matteo Murgia and Valentina Vacca Categories: astro-ph.GA astro-ph.CO Comments: 9 pages, 5 figures - to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)104 \\ The presence of magnetic fields in galaxy clusters has been well established in recent years, and their importance for the understanding of the physical processes at work in the Intra Cluster Medium has been recognized. Halo and relic sources have been detected in several tens clusters. A strong correlation is present between the halo and relic radio power and the X-ray luminosity. Since cluster X-Ray luminosity and mass are related, the correlation between the radio power and X-ray luminosity could derive from a physical dependence of the radio power on the cluster mass, therefore the cluster mass could be a crucial parameter in the formation of these sources. The goal of this project is to investigate the existence of non-thermal structures beyond the Mpc scale, and associated with lower density regions with respect to clusters of galaxies: galaxy filaments connecting rich clusters. We present a piece of evidence of diffuse radio emission in intergalactic filaments. Moreover, we present and discuss the detection of radio emission in galaxy groups and in faint X-Ray clusters, to analyze non-thermal properties in low density regions with physical conditions similar to galaxy filaments. We discuss how SKA1 observations will allow the investigation of this topic and the study of the presence of diffuse radio sources in low density regions. This will be a fundamental step to understand the origin and properties of cosmological magnetic fields. \\ ( http://arxiv.org/abs/1501.01023 , 1044kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01077 Date: Tue, 6 Jan 2015 04:32:46 GMT (3714kb) Title: Observations of the Intergalactic Medium and the Cosmic Web in the SKA era Authors: A. Popping, M. Meyer, L. Staveley-Smith, D. Obreschkow, G. I. Jozsa, D.J. Pisano Categories: astro-ph.GA astro-ph.CO Comments: 21 pages, 6 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)132 \\ The interaction of galaxies with their environment, the Intergalactic Medium (IGM), is an important aspect of galaxy formation. One of the most fundamental, but unanswered questions in the evolution of galaxies is how gas circulates in and around galaxies and how it enters the galaxies to support star formation. We have several lines of evidence that the observed evolution of star formation requires gas accretion from the IGM at all times and on all cosmic scales. This gas remains largely unaccounted for and the outstanding questions are where this gas resides and what the physical mechanisms of accretion are. The gas is expected to be embedded in an extended cosmic web made of sheets and filaments. Such large-scale filaments of gas are expected by cosmological numerical simulations, which have made significant progress in recent years. Such simulations do not only model the large scale structure of the cosmic web, but also investigate the neutral gas component. To truly make significant progress in understanding the distribution of neutral hydrogen in the IGM, column densities of NHI=1018 cm-2 and below have to be probed over large areas on the sky at sub-arcminute resolution. These are the densities of the faintest structures known today around nearby galaxies, though mostly found with single dish telescopes which do not have the resolution to resolve these structures and investigate any kinematics. Existing interferometers lack the collecting power or short baselines to achieve brightness sensitivities typically below NHI=1019 cm-2. Reaching lower column densities with current facilities is feasible, however requires prohibitively long observing times. The SKA will for the first time break these barriers, enabling interferometric observations an order of magnitude deeper than current interferometers and with an order of magnitude better linear resolution than single-dish telescopes. \\ ( http://arxiv.org/abs/1501.01077 , 3714kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01082 Date: Tue, 6 Jan 2015 05:34:14 GMT (2885kb,D) Title: Connecting the Baryons: Multiwavelength Data for SKA HI Surveys Authors: Martin Meyer, Aaron Robotham, Danail Obreschkow, Simon Driver, Lister Staveley-Smith and Martin Zwaan Categories: astro-ph.GA astro-ph.CO Comments: to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)131 \\ The science achievable with SKA HI surveys will be greatly increased through the combination of HI data with that at other wavelengths. These multiwavelength datasets will enable studies to move beyond an understanding of HI gas in isolation to instead understand HI as an integral part of the highly complex baryonic processes that drive galaxy evolution. As they evolve, galaxies experience a host of environmental and feedback influences, many of which can radically impact their gas content. Important processes include: accretion (hot and cold mode, mergers), depletion (star formation, galactic winds, AGN), phase changes (ionised/atomic/molecular), and environmental effects (ram pressure stripping, tidal effects, strangulation). Governing all of these to various extents is the underlying dark matter distribution. In turn, the result of these processes can significantly alter the baryonic states in which material is finally observed (stellar populations, dust, chemistry) and its morphology (galaxy type, bulge/disk ratio, bars, warps, radial profile). To fully understand the evolution of HI and the role it plays in galactic evolution requires the ability to quantify each of these separate processes, and hence to coordinate SKA HI surveys with extensive multi-band photometric and spectroscopic campaigns. In addition, multiwavelength data is essential for statistical methods of HI analysis such as HI stacking and intensity mapping cross-correlations. In this chapter, we examine some of the principal science motivations for acquiring multiwavelength data to match that from the extragalactic SKA HI surveys, and review the currently planned capacity to achieve this (eg. LSST, Euclid, W-FIRST, SPICA, ALMA, and 4MOST). \\ ( http://arxiv.org/abs/1501.01082 , 2885kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01091 Date: Tue, 6 Jan 2015 06:59:58 GMT (1618kb) Title: Cool Outflows and HI absorbers with SKA Authors: Raffaella Morganti, Elaine M. Sadler, Stephen J. Curran and the SKA HI SWG Members Categories: astro-ph.GA Comments: 18 pages, 9 figures. To be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14) 134 \\ HI 21-cm absorption spectroscopy provides a unique probe of the cold neutral gas in normal and active galaxies from redshift z > 6 to the present day. We describe the status of HI absorption studies, the plans for pathfinders/precursors, the expected breakthroughs that will be possible with SKA1, and some limitations set by the current design. \\ ( http://arxiv.org/abs/1501.01091 , 1618kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01130 Date: Tue, 6 Jan 2015 10:34:44 GMT (2967kb) Title: Galactic and Magellanic Evolution with the SKA Authors: Naomi M. McClure-Griffiths, Snezana Stanimirovic, Claire E. Murray, Di Li, John M. Dickey, Enrique Vazquez-Semadeni, Josh E. G. Peek, Mary Putman, Susan E. Clark, Marc-Antoine Miville-Deschenes, Joss Bland-Hawthorn, Lister Staveley-Smith Categories: astro-ph.GA Comments: 25 pages, from "Advancing Astrophysics with the Square Kilometre Array", to appear in Proceedings of Science \\ As we strive to understand how galaxies evolve it is crucial that we resolve physical processes and test emerging theories in nearby systems that we can observe in great detail. Our own Galaxy, the Milky Way, and the nearby Magellanic Clouds provide unique windows into the evolution of galaxies, each with its own metallicity and star formation rate. These laboratories allow us to study with more detail than anywhere else in the Universe how galaxies acquire fresh gas to fuel their continuing star formation, how they exchange gas with the surrounding intergalactic medium, and turn warm, diffuse gas into molecular clouds and ultimately stars. The $\lambda$21-cm line of atomic hydrogen (HI) is an excellent tracer of these physical processes. With the SKA we will finally have the combination of surface brightness sensitivity, point source sensitivity and angular resolution to transform our understanding of the evolution of gas in the Milky Way, all the way from the halo down to the formation of individual molecular clouds. \\ ( http://arxiv.org/abs/1501.01130 , 2967kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01179 Date: Tue, 6 Jan 2015 13:54:31 GMT (148kb) Title: The Physics of the Cold Neutral Medium: Low-frequency Carbon Radio Recombination Lines with the Square Kilometre Array Authors: J. B. R. Oonk, L. K. Morabito, F. Salgado, M. C. Toribio, R. J. van Weeren, A. G. G. M. Tielens, H. J. A. Rottgering Categories: astro-ph.GA Comments: 15 pages, 3 figures, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)139 \\ The Square Kilometre Array (SKA) will transform our understanding of the role of the cold, atomic gas in galaxy evolution. The interstellar medium (ISM) is the repository of stellar ejecta and the birthsite of new stars and, hence, a key factor in the evolution of galaxies over cosmic time. Cold, diffuse, atomic clouds are a key component of the ISM, but so far this phase has been difficult to study, because its main tracer, the HI 21 cm line, does not constrain the basic physical information of the gas (e.g., temperature, density) well. The SKA opens up the opportunity to study this component of the ISM through a complementary tracer in the form of low-frequency (<350 MHz) carbon radio recombination lines (CRRL). These CRRLs provide a sensitive probe of the physical conditions in cold, diffuse clouds. The superb sensitivity, large field of view, frequency resolution and coverage of the SKA allows for efficient surveys of the sky, that will revolutionize the field of low-frequency recombination line studies. By observing these lines with the SKA we will be able determine the thermal balance, chemical enrichment, and ionization rate of the cold, atomic medium from degree-scales down to scales corresponding to individual clouds and filaments in our Galaxy, the Magellanic Clouds and beyond. Furthermore, being sensitive only to the cold, atomic gas, observations of low-frequency CRRLs with the SKA will aid in disentangling the warm and cold constituents of the HI 21 cm emission. \\ ( http://arxiv.org/abs/1501.01179 , 148kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01211 Date: Tue, 6 Jan 2015 15:54:38 GMT (2554kb,D) Title: The SKA view of the Neutral Interstellar Medium in Galaxies Authors: W.J.G. de Blok, F. Fraternali, G.H. Heald, E.A.K. Adams, A. Bosma, B.S. Koribalski and the HI Science Working Group Categories: astro-ph.GA Comments: 22 pages, 4 figures, to appear as part of 'Neutral Hydrogen' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)129 \\ Two major questions in galaxy evolution are how star-formation on small scales leads to global scaling laws and how galaxies acquire sufficient gas to sustain their star formation rates. HI observations with high angular resolution and with sensitivity to very low column densities are some of the important observational ingredients that are currently still missing. Answers to these questions are necessary for a correct interpretation of observations of galaxy evolution in the high-redshift universe and will provide crucial input for the sub-grid physics in hydrodynamical simulations of galaxy evolutions. In this chapter we discuss the progress that will be made with the SKA using targeted observations of nearby individual disk and dwarf galaxies. \\ ( http://arxiv.org/abs/1501.01211 , 2554kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01238 Date: Tue, 6 Jan 2015 17:07:34 GMT (400kb,D) Title: Multiple supermassive black hole systems: SKA's future leading role Authors: Roger Deane (1,2), Zsolt Paragi (3), Matt Jarvis (4,5), Mick\"ael Coriat (1,2), Gianni Bernardi (2,6,7), Sandor Frey (8), Ian Heywood (9,6), Hans-Rainer Kl\"ockner (10), ((1) University of Cape Town, (2) Square Kilometre Array South Africa, (3) Joint Institute for VLBI in Europe, (4) University of Oxford, (5) University of the Western Cape, (6) Rhodes University, (7) Harvard-Smithsonian Center for Astrophysics, (8) F\"OMI Satellite Geodetic Observatory, (9) CSIRO Astronomy and Space Science, (10) Max-Planck-Institut f\"ur Radioastronomie) Categories: astro-ph.GA astro-ph.CO astro-ph.HE Comments: 11 pages, 4 figures. To be published in the proceedings of "Advancing Astrophysics with the Square Kilometre Array", PoS(AASKA14)151, in press \\ Galaxies and supermassive black holes (SMBHs) are believed to evolve through a process of hierarchical merging and accretion. Through this paradigm, multiple SMBH systems are expected to be relatively common in the Universe. However, to date there are poor observational constraints on multiple SMBHs systems with separations comparable to a SMBH gravitational sphere of influence (<< 1 kpc). In this chapter, we discuss how deep continuum observations with the SKA will make leading contributions towards understanding how multiple black hole systems impact galaxy evolution. In addition, these observations will provide constraints on and an understanding of stochastic gravitational wave background detections in the pulsar timing array sensitivity band (nanoHz -microHz). We also discuss how targets for pointed gravitational wave experiments (that cannot be resolved by VLBI) could potentially be found using the large-scale radio-jet morphology, which can be modulated by the presence of a close-pair binary SMBH system. The combination of direct imaging at high angular resolution; low-surface brightness radio-jet tracers; and pulsar timing arrays will allow the SKA to trace black hole binary evolution from separations of a galaxy virial radius down to the sub-parsec level. This large dynamic range in binary SMBH separation will ensure that the SKA plays a leading role in this observational frontier. \\ ( http://arxiv.org/abs/1501.01238 , 400kb) ------------------------------------------------------------------------------ \\ arXiv:1501.01295 Date: Tue, 6 Jan 2015 20:49:29 GMT (1696kb,D) Title: Exploring Neutral Hydrogen and Galaxy Evolution with the SKA Authors: S.-L. Blyth, J.M. van der Hulst, M.A.W. Verheijen, HI SWG Members, B. Catinella, F. Fraternali, M.P. Haynes, K.M. Hess, B.S. Koribalski, C. Lagos, M. Meyer, D. Obreschkow, A. Popping, C. Power, L. Verdes-Montenegro, M. Zwaan Categories: astro-ph.GA Comments: 25 pages, 5 figures, 3 tables. Contribution to the conference 'Advancing Astrophysics with the Square Kilometre Array', June 8-13, 2014, Giardini Naxos, Italy \\ One of the key science drivers for the development of the SKA is to observe the neutral hydrogen, HI, in galaxies as a means to probe galaxy evolution across a range of environments over cosmic time. Over the past decade, much progress has been made in theoretical simulations and observations of HI in galaxies. However, recent HI surveys on both single dish radio telescopes and interferometers, while providing detailed information on global HI properties, the dark matter distribution in galaxies, as well as insight into the relationship between star formation and the interstellar medium, have been limited to the local universe. Ongoing and upcoming HI surveys on SKA pathfinder instruments will extend these measurements beyond the local universe to intermediate redshifts with long observing programmes. We present here an overview of the HI science which will be possible with the increased capabilities of the SKA and which will build upon the expected increase in knowledge of HI in and around galaxies obtained with the SKA pathfinder surveys. With the SKA1 the greatest improvement over our current measurements is the capability to image galaxies at reasonable linear resolution and good column density sensitivity to much higher redshifts (0.2 < z < 1.7). So one will not only be able to increase the number of detections to study the evolution of the HI mass function, but also have the sensitivity and resolution to study inflows and outflows to and from galaxies and the kinematics of the gas within and around galaxies as a function of environment and cosmic time out to previously unexplored depths. The increased sensitivity of SKA2 will allow us to image Milky Way-size galaxies out to redshifts of z=1 and will provide the data required for a comprehensive picture of the HI content of galaxies back to z~2 when the cosmic star formation rate density was at its peak. \\ ( http://arxiv.org/abs/1501.01295 , 1696kb) ------------------------------------------------------------------------------ \\ arXiv:1501.02298 Date: Sat, 10 Jan 2015 01:17:11 GMT (1760kb,D) Title: SKA Deep Polarization and Cosmic Magnetism Authors: A.R. Taylor, Ivan Agudo, Takuya Akahori, Rainer Beck, Bryan Gaensler, George Heald, Melanie Johnston-Hollitt, Mathieu Langer, Lawrence Rudnick, Dongsu Ryu, Anna Scaife, Dominik Schleicher, Jeroen Stil Categories: astro-ph.GA Comments: 9 pages, 3 figures; to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)113 \\ Deep surveys with the SKA1-MID array offer for the first time the opportunity to systematically explore the polarization properties of the microJy source population. Our knowledge of the polarized sky approaching these levels is still very limited. In total intensity the population will be dominated by star-forming and normal galaxies to intermediate redshifts ($z \sim1-2$), and low-luminosity AGN to high redshift. The polarized emission from these objects is a powerful probe of their intrinsic magnetic fields and of their magnetic environments. For redshift of order 1 and above the broad bandwidth of the mid-bands span the Faraday thick and thin regimes allowing study of the intrinsic polarization properties of these objects as well as depolarization from embedded and foreground plasmas. The deep field polarization images will provide Rotation Measures data with very high solid angle density allowing a sensitive statistical analysis of the angular variation of RM on critical arc-minute scales from a magnetic component of Large Scale Structure of the Universe. \\ ( http://arxiv.org/abs/1501.02298 , 1760kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03102 Date: Tue, 13 Jan 2015 18:41:15 GMT (930kb,D) Title: SKA synergy with Microwave Background studies Authors: Carlo Burigana, Paul Alexander, Carlo Baccigalupi, Domingos Barbosa, Alain Blanchard, Adriano De Rosa, Gianfranco de Zotti, Fabio Finelli, Alessandro Gruppuso, Michael Jones, Sabino Matarrese, Alessandro Melchiorri, Diego Molinari, Mattia Negrello, Daniela Paoletti, Francesca Perrotta, Roberto Scaramella, and Tiziana Trombetti Categories: astro-ph.CO Comments: 16 pages, 3 figures. Approved as Chapter in "Advancing Astrophysics with the Square Kilometre Array", June 8-13, 2014, Giardini Naxos, Italy. Submission: August 22, 2014; in revised form: December 23, 2014; approval notification: January 12, 2015. In press on Proceedings of Science (PoS) \\ The extremely high sensitivity and resolution of the Square Kilometre Array (SKA) will be useful for addressing a wide set of themes relevant for cosmology, in synergy with current and future cosmic microwave background (CMB) projects. Many of these themes also have a link with future optical-IR and X-ray observations. We discuss the scientific perspectives for these goals, the instrumental requirements and the observational and data analysis approaches, and identify several topics that are important for cosmology and astrophysics at different cosmic epochs. \\ ( http://arxiv.org/abs/1501.03102 , 930kb) ------------------------------------------------------------------------------ \\ arXiv:1501.02960 Date: Tue, 13 Jan 2015 11:25:10 GMT (2393kb) Title: Synergistic science with Euclid and SKA : the nature and history of Star Formation Authors: Paolo Ciliegi (INAF-OABO) and Sandro Bardelli (INAF-OABO) Categories: astro-ph.GA Comments: 13 pages, 3 figures, to appear in proceedings of "Advancing Astrophysics with the Square Kilometre Array" PoS(AASKA14)150 \\ We explored the impact of the synergy between the Euclid near-infrared photometric surveys and the SKA radio continuum surveys on the studies of the cosmic star formation. The Euclid satellite is expected to perform a Wide and Deep photometric surveys to an infrared limit of H ~ 24 and H ~ 26 respectively and a spectroscopy survey with a flux limit of $\sim 3 \times 10^{-16}$ erg cm$^{-2}$ s$^{-1}$ in the Halpha line. Combining the H band Euclid selected samples with the ground based ancillary data (fundamental for the SFR estimation) we will be able to detect the star forming galaxies down to SFRs of order of unit to z ~ 2 and down to SFR ~ 10 to z ~ 3, sampling the majority of the star forming galaxies up to z ~3 and beyond and placing definitive constraints on the star formation history of the universe at z<4-5 (is there a peak a z ~2 or a plateau at 1 10 GeV sources, with a detection rate of 83%. Moreover, we are cross correlating the Fermi catalogs with the MWA commissioning survey: when faint gamma-ray sources are considered, pure positional coincidence is not significant enough for selecting counterparts and we need an additional physical criterion to pinpoint the right object. It can be radio spectral index, variability, polarization, or compactness, needing high angular resolution in SKA1-MID; timing studies can also reveal pulsars, which are often found from dedicated searches of unidentified gamma-ray sources. SKA will be the ideal instrument for investigating these characteristics in conjunction with CTA. (abridged) \\ ( http://arxiv.org/abs/1501.03330 , 81kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03820 Date: Thu, 15 Jan 2015 21:00:13 GMT (144kb,D) Title: Testing foundations of modern cosmology with SKA all-sky surveys Authors: Dominik J. Schwarz, David Bacon, Song Chen, Chris Clarkson, Dragan Huterer, Martin Kunz, Roy Maartens, Alvise Raccanelli, Matthias Rubart, Jean-Luc Starck Categories: astro-ph.CO gr-qc Comments: SKA Cosmology Chapter, Advancing Astrophysics with the Square Kilometre Array (AASKA14) Conference, Giardini Naxos, Italy / June 9th -13th, 2014 \\ Continuum and HI surveys with the Square Kilometre Array (SKA) will allow us to probe some of the most fundamental assumptions of modern cosmology, including the Cosmological Principle. SKA all-sky surveys will map an enormous slice of space-time and reveal cosmology at superhorizon scales and redshifts of order unity. We illustrate the potential of these surveys and discuss the prospects to measure the cosmic radio dipole at high fidelity. We outline several potentially transformational tests of cosmology to be carried out by means of SKA all-sky surveys. \\ ( http://arxiv.org/abs/1501.03820 , 144kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03821 Date: Thu, 15 Jan 2015 21:00:14 GMT (191kb,D) Title: Measuring redshift-space distortions with future SKA surveys Authors: Alvise Raccanelli (1,2,3), Philip Bull (4), Stefano Camera (5,6), David Bacon (7), Chris Blake (8), Olivier Dore (2,3), Pedro Ferreira (9), Roy Maartens (10,7), Mario Santos (10,11,6), Matteo Viel (12,13), Gong-bo Zhao (14,7), ((1) Johns Hopkins University, (2) JPL, (3) Caltech, (4) Oslo, (5) Manchester, (6) CENTRA, (7) ICG, (8) Swinburne, (9) Oxford, (10) UWC, (11) SKA SA, (12) INAF, (13) INFN, (14) NAOC) Categories: astro-ph.CO gr-qc Comments: 19 pages, 4 figures. This article is part of the "Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014" \\ The peculiar motion of galaxies can be a particularly sensitive probe of gravitational collapse. As such, it can be used to measure the dynamics of dark matter and dark energy as well the nature of the gravitational laws at play on cosmological scales. Peculiar motions manifest themselves as an overall anisotropy in the measured clustering signal as a function of the angle to the line-of-sight, known as redshift-space distortion (RSD). Limiting factors in this measurement include our ability to model non-linear galaxy motions on small scales and the complexities of galaxy bias. The anisotropy in the measured clustering pattern in redshift-space is also driven by the unknown distance factors at the redshift in question, the Alcock-Paczynski distortion. This weakens growth rate measurements, but permits an extra geometric probe of the Hubble expansion rate. In this chapter we will briefly describe the scientific background to the RSD technique, and forecast the potential of the SKA phase 1 and the SKA2 to measure the growth rate using both galaxy catalogues and intensity mapping, assessing their competitiveness with current and future optical galaxy surveys. \\ ( http://arxiv.org/abs/1501.03821 , 191kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03822 Date: Thu, 15 Jan 2015 21:00:16 GMT (203kb,D) Title: Real time cosmology - A direct measure of the expansion rate of the Universe Authors: H.-R. Kl\"ockner, D. Obreschkow, C. Martins, A. Raccanelli, D. Champion, A. Roy, A. Lobanov, J. Wagner, R. Keller Categories: astro-ph.CO Comments: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ In recent years cosmology has undergone a revolution, with precise measurements of the microwave background radiation, large galaxy redshift surveys, and the discovery of the recent accelerated expansion of the Universe using observations of distant supernovae. In this light, the SKA enables us to do an ultimate test in cosmology by measuring the expansion rate of the Universe in real time. This can be done by a rather simple experiment of observing the neutral hydrogen (HI) signal of galaxies at two different epochs. The signal will encounter a change in frequency imprinted as the Universe expands over time and thus monitoring the drift in frequencies will provide a real time measure of the cosmic acceleration. Over a period of 12 years one would expected a frequency shift of the order of 0.1 Hz assuming a standard Lambda-CDM cosmology. Based on the sensitivity estimates of the SKA and the number counts of the expected HI galaxies, it is shown that the number counts are sufficiently high to compensate for the observational uncertainties of the measurements and hence allow a statistical detection of the frequency shift. [abstract abridged] \\ ( http://arxiv.org/abs/1501.03822 , 203kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03823 Date: Thu, 15 Jan 2015 21:00:18 GMT (262kb,D) Title: Foreground Subtraction in Intensity Mapping with the SKA Authors: Laura Wolz, Filipe B. Abdalla, David Alonso, Chris Blake, Philip Bull, Tzu-Ching Chang, Pedro G. Ferreira, Cheng-Yu Kuo, Marios G. Santos and Richard Shaw Categories: astro-ph.CO Comments: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ 21cm intensity mapping experiments aim to observe the diffuse neutral hydrogen (HI) distribution on large scales which traces the Cosmic structure. The Square Kilometre Array (SKA) will have the capacity to measure the 21cm signal over a large fraction of the sky. However, the redshifted 21cm signal in the respective frequencies is faint compared to the Galactic foregrounds produced by synchrotron and free-free electron emission. In this article, we review selected foreground subtraction methods suggested to effectively separate the 21cm signal from the foregrounds with intensity mapping simulations or data. We simulate an intensity mapping experiment feasible with SKA phase 1 including extragalactic and Galactic foregrounds. We give an example of the residuals of the foreground subtraction with a independent component analysis and show that the angular power spectrum is recovered within the statistical errors on most scales. Additionally, the scale of the Baryon Acoustic Oscillations is shown to be unaffected by foreground subtraction. \\ ( http://arxiv.org/abs/1501.03823 , 262kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03825 Date: Thu, 15 Jan 2015 21:01:14 GMT (1126kb,D) Title: Cosmology with SKA Radio Continuum Surveys Authors: Matt J. Jarvis (1,2), David Bacon (3), Chris Blake (4), Michael L. Brown (5), Sam N. Lindsay (1), Alvise Raccanelli (6,7,8), Mario Santos (2,9), Dominik Schwarz (10) ((1) Oxford, (2) University of the Western Cape, (3) ICG, Portsmouth, (4) Swinburne, (5) Manchester, (6) Johns Hopkins, (7) JPL, (8) Caltech, (9) SKA South Africa, (10) Bielefield) Categories: astro-ph.CO Comments: SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ Radio continuum surveys have, in the past, been of restricted use in cosmology. Most studies have concentrated on cross-correlations with the cosmic microwave background to detect the integrated Sachs-Wolfe effect, due to the large sky areas that can be surveyed. As we move into the SKA era, radio continuum surveys will have sufficient source density and sky area to play a major role in cosmology on the largest scales. In this chapter we summarise the experiments that can be carried out with the SKA as it is built up through the coming decade. We show that the SKA can play a unique role in constraining the non-Gaussianity parameter to \sigma(f_NL) ~ 1, and provide a unique handle on the systematics that inhibit weak lensing surveys. The SKA will also provide the necessary data to test the isotropy of the Universe at redshifts of order unity and thus evaluate the robustness of the cosmological principle.Thus, SKA continuum surveys will turn radio observations into a central probe of cosmological research in the coming decades. \\ ( http://arxiv.org/abs/1501.03825 , 1126kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03828 Date: Thu, 15 Jan 2015 21:01:59 GMT (848kb,D) Title: Weak gravitational lensing with the Square Kilometre Array Authors: M. L. Brown, D. J. Bacon, S. Camera, I. Harrison, B. Joachimi, R. B. Metcalf, A. Pourtsidou, K. Takahashi, J. A. Zuntz, F. B. Abdalla, S. Bridle, M. Jarvis, T. D. Kitching, L. Miller, P. Patel Categories: astro-ph.CO Comments: 19 pages, 6 figures. Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014 \\ We investigate the capabilities of various stages of the SKA to perform world-leading weak gravitational lensing surveys. We outline a way forward to develop the tools needed for pursuing weak lensing in the radio band. We identify the key analysis challenges and the key pathfinder experiments that will allow us to address them in the run up to the SKA. We identify and summarize the unique and potentially very powerful aspects of radio weak lensing surveys, facilitated by the SKA, that can solve major challenges in the field of weak lensing. These include the use of polarization and rotational velocity information to control intrinsic alignments, and the new area of weak lensing using intensity mapping experiments. We show how the SKA lensing surveys will both complement and enhance corresponding efforts in the optical wavebands through cross-correlation techniques and by way of extending the reach of weak lensing to high redshift. \\ ( http://arxiv.org/abs/1501.03828 , 848kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03840 Date: Thu, 15 Jan 2015 22:26:14 GMT (362kb) Title: Model-independent constraints on dark energy and modified gravity with the SKA Authors: Gong-Bo Zhao, David Bacon, Roy Maartens, Mario Santos, Alvise Raccanelli Categories: astro-ph.CO Comments: 13 pages, 5 figures. This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ Employing a nonparametric approach of the principal component analysis (PCA), we forecast the future constraint on the equation of state $w(z)$ of dark energy, and on the effective Newton constant $\mu(k,z)$, which parameterise the effect of modified gravity, using the planned SKA HI galaxy survey. Combining with the simulated data of Planck and Dark Energy Survey (DES), we find that SKA Phase 1 (SKA1) and SKA Phase 2 (SKA2) can well constrain $3$ and $5$ eigenmodes of $w(z)$ respectively. The errors of the best measured modes can be reduced to 0.04 and 0.023 for SKA1 and SKA2 respectively, making it possible to probe dark energy dynamics. On the other hand, SKA1 and SKA2 can constrain $7$ and $20$ eigenmodes of $\mu(k,z)$ respectively within 10\% sensitivity level. Furthermore, 2 and 7 modes can be constrained within sub percent level using SKA1 and SKA2 respectively. This is a significant improvement compared to the combined datasets without SKA. \\ ( http://arxiv.org/abs/1501.03840 , 362kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03848 Date: Thu, 15 Jan 2015 23:11:36 GMT (567kb,D) Title: Cross correlation surveys with the Square Kilometre Array Authors: Donnacha Kirk, Aur\'elien Benoit-L\'evy, Filipe B. Abdalla, Philip Bull, Benjamin Joachimi Categories: astro-ph.CO Comments: 12 pages, 3 figures. This article is part of the 'Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ By the time that the first phase of the Square Kilometre Array is deployed it will be able to perform state of the art Large Scale Structure (LSS) as well as Weak Gravitational Lensing (WGL) measurements of the distribution of matter in the Universe. In this chapter we concentrate on the synergies that result from cross-correlating these different SKA data products as well as external correlation with the weak lensing measurements available from CMB missions. We show that the Dark Energy figures of merit obtained individually from WGL/LSS measurements and their independent combination is significantly increased when their full cross-correlations are taken into account. This is due to the increased knowledge of galaxy bias as a function of redshift as well as the extra information from the different cosmological dependences of the cross-correlations. We show that the cross-correlation between a spectroscopic LSS sample and a weak lensing sample with photometric redshifts can calibrate these same photometric redshifts, and their scatter, to high accuracy by modelling them as nuisance parameters and fitting them simultaneously cosmology. Finally we show that Modified Gravity parameters are greatly constrained by this cross-correlations because weak lensing and redshift space distortions (from the LSS survey) break strong degeneracies in common parameterisations of modified gravity. \\ ( http://arxiv.org/abs/1501.03848 , 567kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03851 Date: Thu, 15 Jan 2015 23:38:36 GMT (185kb) Title: Cosmology on the Largest Scales with the SKA Authors: S. Camera, A. Raccanelli, P. Bull, D. Bertacca, X. Chen, P.G. Ferreira, M. Kunz, R. Maartens, Y. Mao, M.G. Santos, P.R. Shapiro, M. Viel and Y. Xu Categories: astro-ph.CO gr-qc Comments: 18 pages, 3 figures. This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ The study of the Universe on ultra-large scales is one of the major science cases for the Square Kilometre Array (SKA). The SKA will be able to probe a vast volume of the cosmos, thus representing a unique instrument, amongst next-generation cosmological experiments, for scrutinising the Universe's properties on the largest cosmic scales. Probing cosmic structures on extremely large scales will have many advantages. For instance, the growth of perturbations is well understood for those modes, since it falls fully within the linear regime. Also, such scales are unaffected by the poorly understood feedback of baryonic physics. On ultra-large cosmic scales, two key effects become significant: primordial non-Gaussianity and relativistic corrections to cosmological observables. Moreover, if late-time acceleration is driven not by dark energy but by modifications to general relativity, then such modifications should become apparent near and above the horizon scale. As a result, the SKA is forecast to deliver transformational constraints on non-Gaussianity and to probe gravity on super-horizon scales for the first time. \\ ( http://arxiv.org/abs/1501.03851 , 185kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03859 Date: Fri, 16 Jan 2015 00:46:57 GMT (3575kb) Title: Overview of Complementarity and Synergy with Other Wavelengths in Cosmology in the SKA era Authors: Keitaro Takahashi, Michael L. Brown, Carlo Burigana, Carole A. Jackson, Matt Jarvis, Thomas D. Kitching, Jean-Paul Kneib, Masamune Oguri, Simon Prunet, Huanyuan Shan, Jean-Luc Starck, and Daisuke Yamauchi Categories: astro-ph.CO Comments: 13 pages, 4 figures. This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ We give an overview of complementarity and synergy in cosmology between the Square Kilometre Array and future survey projects in other wavelengths. In the SKA era, precision cosmology will be limited by systematic errors and cosmic variance, rather than statistical errors. However, combining and/or cross-correlating multi-wavelength data, from the SKA to the cosmic microwave background, optical/infrared and X-ray, substantially reduce these limiting factors. In this chapter, we summarize future survey projects and show highlights of complementarity and synergy, which can be very powerful to probe major cosmological problems such as dark energy, modified gravity and primordial non-Gaussianity. \\ ( http://arxiv.org/abs/1501.03859 , 3575kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03892 Date: Fri, 16 Jan 2015 06:52:33 GMT (1543kb,D) Title: Weak Lensing Simulations for the SKA Authors: Prina Patel, Ian Harrison, Sphesihle Makhathini, Filipe Abdalla, David Bacon, Michael L. Brown, Ian Heywood, Matt Jarvis, Oleg Smirnov Categories: astro-ph.CO astro-ph.IM Comments: SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014 \\ Weak gravitational lensing measurements are traditionally made at optical wavelengths where many highly resolved galaxy images are readily available. However, the Square Kilometre Array (SKA) holds great promise for this type of measurement at radio wavelengths owing to its greatly increased sensitivity and resolution over typical radio surveys. The key to successful weak lensing experiments is in measuring the shapes of detected sources to high accuracy. In this document we describe a simulation pipeline designed to simulate radio images of the quality required for weak lensing, and will be typical of SKA observations. We provide as input, images with realistic galaxy shapes which are then simulated to produce images as they would have been observed with a given radio interferometer. We exploit this pipeline to investigate various stages of a weak lensing experiment in order to better understand the effects that may impact shape measurement. We first show how the proposed SKA1-Mid array configurations perform when we compare the (known) input and output ellipticities. We then investigate how making small changes to these array configurations impact on this input-outut ellipticity comparison. We also demonstrate how alternative configurations for SKA1-Mid that are smaller in extent, and with a faster survey speeds produce similar performance to those originally proposed. We then show how a notional SKA configuration performs in the same shape measurement challenge. Finally, we describe ongoing efforts to utilise our simulation pipeline to address questions relating to how applicable current (mostly originating from optical data) shape measurement techniques are to future radio surveys. As an alternative to such image plane techniques, we lastly discuss a shape measurement technique based on the shapelets formalism that reconstructs the source shapes directly from the visibility data. \\ ( http://arxiv.org/abs/1501.03892 , 1543kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03977 Date: Fri, 16 Jan 2015 13:29:49 GMT (1219kb,D) Title: Synergy between the Large Synoptic Survey Telescope and the Square Kilometre Array Authors: David Bacon, Sarah Bridle, Filipe B. Abdalla, Michael Brown, Philip Bull, Stefano Camera, Rob Fender, Keith Grainge, Zeljko Ivezic, Matt Jarvis, Neal Jackson, Donnacha Kirk, Bob Mann, Jason McEwen, John McKean, Jeffrey A. Newman, Alvise Raccanelli, Martin Sahlen, Mario Santos, Anthony Tyson, Gong-Bo Zhao Categories: astro-ph.CO Comments: SKA Synergies Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014 \\ We provide an overview of the science benefits of combining information from the Square Kilometre Array (SKA) and the Large Synoptic Survey Telescope (LSST). We first summarise the capabilities and timeline of the LSST and overview its science goals. We then discuss the science questions in common between the two projects, and how they can be best addressed by combining the data from both telescopes. We describe how weak gravitational lensing and galaxy clustering studies with LSST and SKA can provide improved constraints on the causes of the cosmological acceleration. We summarise the benefits to galaxy evolution studies of combining deep optical multi-band imaging with radio observations. Finally, we discuss the excellent match between one of the most unique features of the LSST, its temporal cadence in the optical waveband, and the time resolution of the SKA. \\ ( http://arxiv.org/abs/1501.03977 , 1219kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03978 Date: Fri, 16 Jan 2015 13:34:24 GMT (5529kb) Title: Euclid & SKA Synergies Authors: Thomas D. Kitching, David Bacon, Michael L. Brown, Philip Bull, Jason D. McEwen, Masamune Oguri, Roberto Scaramella, Keitaro Takahashi, Kinwah Wu, Daisuke Yamauchi Categories: astro-ph.CO Comments: This article is part of the 'SKA Synergies Chapter, Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ Over the past few years two of the largest and highest fidelity experiments conceived have been approved for construction: Euclid is an ESA M-Class mission that will map three-quarters of the extra galactic sky with Hubble Space Telescope resolution optical and NIR imaging, and NIR spectroscopy, its scientific aims (amongst others) are to create a map of the dark Universe and to determine the nature of dark energy. The Square Kilometre Array (SKA) has similar scientific aims (and others) using radio wavelength observations. The two experiments are synergistic in several respects, both through the scientific objectives and through the control of systematic effects. SKA Phase-1 and Euclid will be commissioned on similar timescales offering an exciting opportunity to exploit synergies between these facilities. \\ ( http://arxiv.org/abs/1501.03978 , 5529kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03989 Date: Fri, 16 Jan 2015 14:33:23 GMT (350kb,D) Title: Cosmology with a SKA HI intensity mapping survey Authors: Mario G. Santos, Philip Bull, David Alonso, Stefano Camera, Pedro G. Ferreira, Gianni Bernardi, Roy Maartens, Matteo Viel, Francisco Villaescusa-Navarro, Filipe B. Abdalla, Matt Jarvis, R. Benton Metcalf, A. Pourtsidou, Laura Wolz Categories: astro-ph.CO astro-ph.IM gr-qc Comments: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ HI intensity mapping (IM) is a novel technique capable of mapping the large-scale structure of the Universe in three dimensions and delivering exquisite constraints on cosmology, by using HI as a biased tracer of the dark matter density field. This is achieved by measuring the intensity of the redshifted 21cm line over the sky in a range of redshifts without the requirement to resolve individual galaxies. In this chapter, we investigate the potential of SKA1 to deliver HI intensity maps over a broad range of frequencies and a substantial fraction of the sky. By pinning down the baryon acoustic oscillation and redshift space distortion features in the matter power spectrum -- thus determining the expansion and growth history of the Universe -- these surveys can provide powerful tests of dark energy models and modifications to General Relativity. They can also be used to probe physics on extremely large scales, where precise measurements of spatial curvature and primordial non-Gaussianity can be used to test inflation; on small scales, by measuring the sum of neutrino masses; and at high redshifts where non-standard evolution models can be probed. We discuss the impact of foregrounds as well as various instrumental and survey design parameters on the achievable constraints. In particular we analyse the feasibility of using the SKA1 autocorrelations to probe the large-scale signal. \\ ( http://arxiv.org/abs/1501.03989 , 350kb) ------------------------------------------------------------------------------ \\ arXiv:1501.03990 Date: Fri, 16 Jan 2015 14:34:28 GMT (248kb) Title: HI galaxy simulations for the SKA: number counts and bias Authors: Mario G. Santos, David Alonso, Philip Bull, Marta Silva, Sahba Yahya Categories: astro-ph.CO astro-ph.IM Comments: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ This chapter describes the assumed specifications and sensitivities for HI galaxy surveys with SKA1 and SKA2. It addresses the expected galaxy number densities based on available simulations as well as the clustering bias over the underlying dark matter. It is shown that a SKA1 HI galaxy survey should be able to find around $5\times 10^6$ galaxies over 5,000 deg$^2$ (up to $z\sim 0.8$), while SKA2 should find $\sim 10^9$ galaxies over 30,000 deg$^2$ (up to $z\sim 2.5$). The numbers presented here have been used throughout the cosmology chapters for forecasting. \\ ( http://arxiv.org/abs/1501.03990 , 248kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04035 Date: Fri, 16 Jan 2015 16:37:39 GMT (1611kb,D) Title: Cosmology from HI galaxy surveys with the SKA Authors: Filipe B. Abdalla, Philip Bull, Stefano Camera, Aur\'elien Benoit-L\'evy, Benjamin Joachimi, Donnacha Kirk, Hans-Rainer Kl\"ockner, Roy Maartens, Alvise Raccanelli, Mario G. Santos, Gong-Bo Zhao, for the Cosmology SWG Categories: astro-ph.CO Comments: 16 pages, 8 figures. This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014' \\ The Square Kilometer Array (SKA) has the potential to produce galaxy redshift surveys which will be competitive with other state of the art cosmological experiments in the next decade. In this chapter we summarise what capabilities the first and the second phases of the SKA will be able to achieve in its current state of design. We summarise the different cosmological experiments which are outlined in further detail in other chapters of this Science Book. The SKA will be able to produce competitive Baryonic Oscillation (BAOs) measurements in both its phases. The first phase of the SKA will provide similar measurements as optical and IR experiments with completely different systematic effects whereas the second phase being transformational in terms of its statistical power. The SKA will produce very accurate Redshift Space Distortions (RSD) measurements, being superior to other experiments at lower redshifts, due to the large number of galaxies. Cross correlations of the galaxy redshift data from the SKA with radio continuum surveys and optical surveys will provide extremely good calibration of photometric redshifts as well as extremely good bounds on modifications of gravity. Basing on a Principle Component Analysis (PCA) approach, we find that the SKA will be able to provide competitive constraints on dark energy and modified gravity models. Due to the large area covered the SKA it will be a transformational experiment in measuring physics from the largest scales such as non-Gaussian signals from $\textrm{f}_{\textrm{nl}}$. Finally, the SKA might produce the first real time measurement of the redshift drift. The SKA will be a transformational machine for cosmology as it grows from an early Phase 1 to its full power. \\ ( http://arxiv.org/abs/1501.04035 , 1611kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04076 Date: Fri, 16 Jan 2015 18:35:23 GMT (1231kb,D) Title: Cosmology with the SKA -- overview Authors: Roy Maartens, Filipe B. Abdalla, Matt Jarvis, Mario G. Santos, for the SKA Cosmology SWG Categories: astro-ph.CO gr-qc Comments: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014'. This is the overview chapter \\ The new frontier of cosmology will be led by three-dimensional surveys of the large-scale structure of the Universe. Based on its all-sky surveys and redshift depth, the SKA is destined to revolutionize cosmology, in combination with future optical/ infrared surveys such as Euclid and LSST. Furthermore, we will not have to wait for the full deployment of the SKA in order to see transformational science. In the first phase of deployment (SKA1), all-sky HI intensity mapping surveys and all-sky continuum surveys are forecast to be at the forefront on the major questions of cosmology. We give a broad overview of the major contributions predicted for the SKA. The SKA will not only deliver precision cosmology -- it will also probe the foundations of the standard model and open the door to new discoveries on large-scale features of the Universe. \\ ( http://arxiv.org/abs/1501.04076 , 1231kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04088 Date: Fri, 16 Jan 2015 20:02:31 GMT (854kb,D) Title: Measuring baryon acoustic oscillations with future SKA surveys Authors: Philip Bull, Stefano Camera, Alvise Raccanelli, Chris Blake, Pedro G. Ferreira, Mario G. Santos, Dominik J. Schwarz Categories: astro-ph.CO Comments: 16 pages, 4 figures. For the busy reader: see Fig. 3. Submitted on behalf of the SKA Cosmology Science working group, for the conference "Advancing Astrophysics with the SKA" (AASKA14), Giardini-Naxos, Italy, June 9th-13th 2014 \\ The imprint of baryon acoustic oscillations (BAO) in large-scale structure can be used as a standard ruler for mapping out the cosmic expansion history, and hence for testing cosmological models. In this article we briefly describe the scientific background to the BAO technique, and forecast the potential of the Phase 1 and 2 SKA telescopes to perform BAO surveys using both galaxy catalogues and intensity mapping, assessing their competitiveness with current and future optical galaxy surveys. We find that a 25,000 sq. deg. intensity mapping survey on a Phase 1 array will preferentially constrain the radial BAO, providing a highly competitive 2% constraint on the expansion rate at z ~ 2. A 30,000 sq. deg. galaxy redshift survey on SKA2 will outperform all other planned experiments for z < 1.4. \\ ( http://arxiv.org/abs/1501.04088 , 854kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04104 Date: Fri, 16 Jan 2015 21:00:05 GMT (72kb) Title: Bulk Flows and End of the Dark Ages with the SKA Authors: Umberto Maio, Benedetta Ciardi, Leon V. E. Koopmans Categories: astro-ph.CO astro-ph.GA Comments: Accepted for publication in the SKA Science Book "Advancing Astrophysics with the Square Kilometre Array", to appear in 2015 \\ The early Universe is a precious probe of the birth of primordial objects, first star formation events and consequent production of photons and heavy elements. Higher-order corrections to the cosmological linear perturbation theory predicts the formation of coherent supersonic gaseous streaming motions at decoupling time. These bulk flows impact the gas cooling process and determine a cascade effect on the whole baryon evolution. By analytical estimates and N-body hydrodynamical chemistry numerical simulations including atomic and molecular evolution, gas cooling, star formation, feedback effects and metal spreading for individual species from different stellar populations according to the proper yields and lifetimes, we discuss the role of these primordial bulk flows at the end of the dark ages and their detectable impacts during the first Gyr in view of the upcoming SKA mission. Early bulk flows can inhibit molecular gas cooling capabilities, suppressing star formation, metal spreading and the abundance of small primordial galaxies in the infant Universe. This can determine a delay in the re-ionization process and in the heating of neutral hydrogen making the observable HI signal during cosmic evolution patchier and noisier. The planned SKA mission will represent a major advance over existing instruments, since it will be able to probe the effects on HI 21cm at z ~ 6-20 and on molecular line emissions from first collapsing sites at z ~ 20-40. Therefore, it will be optimal to address the effects of primordial streaming motions on early baryon evolution and to give constraints on structure formation in the first Gyr. \\ ( http://arxiv.org/abs/1501.04104 , 72kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04106 Date: Fri, 16 Jan 2015 21:00:09 GMT (4581kb,D) Title: Constraining the Astrophysics of the Cosmic Dawn and the Epoch of Reionization with the SKA Authors: Andrei Mesinger, Andrea Ferrara, Bradley Greig, Ilian Iliev, Garrelt Mellema, Jonathan Pritchard, Mario G. Santos, for the SKA EoR/CD Science Team Categories: astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The Square Kilometre Array (SKA) will offer an unprecedented view onto the early Universe, using interferometric observations of the redshifted 21cm line. The 21cm line probes the thermal and ionization state of the cosmic gas, which is governed by the birth and evolution of the first structures in our Universe. Here we show how the evolution of the 21cm signal will allow us to study when the first generations of galaxies appeared, what were their properties, and what was the structure of the intergalactic medium. We highlight qualitative trends which will offer robust insights into the early Universe. \\ ( http://arxiv.org/abs/1501.04106 , 4581kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04203 Date: Sat, 17 Jan 2015 15:06:59 GMT (2919kb,D) Title: HI tomographic imaging of the Cosmic Dawn and Epoch of Reionization with SKA Authors: Garrelt Mellema, Le\'on Koopmans, Hemant Shukla, Kanan K. Datta, Andrei Mesinger and Suman Majumdar, on behalf of the CD/EoR Science Working Group Categories: astro-ph.CO Comments: 14 pages, 3 figures. Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015. PoS(AASKA14)010 \\ We provide an overview of 21cm tomography of the Cosmic Dawn and Epoch of Reionization as possible with SKA-Low. We show why tomography is essential for studying CD/EoR and present the scales which can be imaged at different frequencies for the different phases of SKA- Low. Next we discuss the different ways in which tomographic data can be analyzed. We end with an overview of science questions which can only be answered by tomography, ranging from the characterization of individual objects to understanding the global processes shaping the Universe during the CD/EoR \\ ( http://arxiv.org/abs/1501.04203 , 2919kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04213 Date: Sat, 17 Jan 2015 17:20:11 GMT (5321kb) Title: Epoch of Reionization modelling and simulations for SKA Authors: Ilian T. Iliev (Sussex), Mario G. Santos (Western Cape), Andrei Mesinger (SNS), Suman Majumdar, Garrelt Mellema (Stockholm) Categories: astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ In this chapter we provide an overview of the current status of the simulations and modelling of the Cosmic Dawn and Epoch of Reionization. We discuss the modelling requirements as dictated by the characteristic scales of the problem and the SKA instrumental properties and the planned survey parameters. Current simulations include most of the relevant physical processes. They can follow the full nonlinear dynamics and are now reaching the required scale and dynamic range, although small-scale physics still needs to be included at sub-grid level. However, despite a significant progress in developing novel numerical methods for efficient utilization of current hardware they remain quite computationally expensive. In response, a number of alternative approaches, particularly semi-analytical/semi-numerical methods, have been developed. While necessarily more approximate, if appropriately constructed and calibrated on simulations they could be used to quickly explore the vast parameter space available. Further work is still required on including some physical processes in both simulations and semi-analytical modelling. This hybrid approach of fast, approximate modelling calibrated on numerical simulations can then be used to construct large libraries of reionization models for reliable interpretation of the observational data. \\ ( http://arxiv.org/abs/1501.04213 , 5321kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04246 Date: Sat, 17 Jan 2015 23:50:41 GMT (3029kb,D) Title: Imaging HII Regions from Galaxies and Quasars During Reionisation with SKA Authors: Stuart Wyithe, Paul M. Geil and Hansik Kim Categories: astro-ph.CO Comments: 13 pages, 6 figures, accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The ionisation structure of the Intergalactic Medium (IGM) during reionisation is sensitive to the unknown galaxy formation physics that prevailed at that time. This structure introduces non-Gaussian statistics into the redshifted 21 cm fluctuation amplitudes that can only be studied through tomographic imaging, which will clearly discriminate between different galaxy formation scenarios. Imaging the ionisation structure and cosmological HII regions during reionisation is therefore a key goal for the SKA. For example, the SKA1-LOW baseline design with a 1 km diameter core will resolve HII regions expected from galaxy formation models which include strong feedback on low-mass galaxy formation. Imaging the smaller HII regions that result from galaxy formation in the absence of SNe feedback will also be possible for SKA1-LOW in the later stages of reionisation, but may require the greater sensitivity of SKA early in the reionisation era. In addition to having baselines long enough to resolve the HII regions, the field of view for SKA1-LOW reionisation experiments should be at least several degrees in order to image the largest HI structures towards the end of reionisation. The baseline design with 35 meter diameter stations has a field of view within a single primary pointing which is sufficient for this purpose. \\ ( http://arxiv.org/abs/1501.04246 , 3029kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04247 Date: Sun, 18 Jan 2015 00:24:13 GMT (238kb,D) Title: SKA - EoR correlations and cross-correlations: kSZ, radio galaxies, and NIR background Authors: Vibor Jelic, Benedetta Ciardi, Elizabeth Fernandez, Hiroyuki Tashiro and Dijana Vrbanec Categories: astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The Universe's Cosmic Dawn (CD) and Epoch of Reionization (EoR) can be studied using a number of observational probes that provide complementary or corroborating information. Each of these probes suffers from its own systematic and statistical uncertainties. It is therefore useful to consider the mutual information that these data sets contain. In this paper, we discuss a potential of cross-correlations between the SKA cosmological 21 cm data with: (i) the kinetic Sunyaev- Zel'dovich (kSZ) effect in the CMB data; (ii) the galaxy surveys; and (iii) near infrared (NIR) backgrounds. \\ ( http://arxiv.org/abs/1501.04247 , 238kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04291 Date: Sun, 18 Jan 2015 12:39:59 GMT (697kb,D) Title: Cosmology from the EoR/Cosmic Dawn with the SKA Authors: Jonathan Pritchard, Kiyotomo Ichiki, Andrei Mesinger, Robert Benton Metcalf, Alkistis Pourtsidou, Mario Santos, Filipe Abdalla, Tzu-Ching Chang, Xuelei Chen, Jochen Weller, Saleem Zaroubi Categories: astro-ph.CO Comments: 19 pages, 8 figures. Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The SKA will build upon early detections of the EoR by precursor instruments, such as MWA, PAPER, and LOFAR, and planned instruments, such as HERA, to make the first high signal-to-noise measurements of fluctuations in the 21 cm brightness temperature from both reionization and the cosmic dawn. This will allow both imaging and statistical maps of the 21cm signal at redshifts z = 6 - 27 and constrain the underlying cosmology and evolution of the density field. This era includes nearly 60% of the (in principle) observable volume of the Universe and many more linear modes than the CMB, presenting an opportunity for SKA to usher in a new level of precision cosmology. This optimistic picture is complicated by the need to understand and remove the effect of astrophysics, so that systematics rather than statistics will limit constraints. This chapter describes the cosmological, as opposed to astrophysical, information available to SKA. Key areas for discussion include: cosmological parameters constraints using 21cm fluctuations as a tracer of the density field; lensing of the 21cm signal, constraints on heating via exotic physics such as decaying or annihilating dark matter; impact of fundamental physics such as non-Gaussianity or warm dark matter on the source population; and constraints on the bulk flows arising from the decoupling of baryons and photons at z = 1000. The chapter explores the path to separating cosmology from astrophysics, for example via velocity space distortions and separation in redshift. We discuss new opportunities for extracting cosmology made possible by the sensitivity of SKA Phase 1 and explores the advances achievable with SKA2. \\ ( http://arxiv.org/abs/1501.04291 , 697kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04425 Date: Mon, 19 Jan 2015 09:09:11 GMT (117kb) Title: 21cm Forest with the SKA Authors: Benedetta Ciardi (MPA), Susumu Inoue (University of Tokyo), Katherine J. Mack (University of Melbourne), Yidong Xu (Chinese Academy of Sciences), Gianni Bernardi (SKA SA) Categories: astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015; 10 pages, 5 figures; the manuscript is based on Ciardi et al., 2013, MNRAS, 428, 1755 \\ An alternative to both the tomography technique and the power spectrum approach is to search for the 21cm forest, that is the 21cm absorption features against high-z radio loud sources caused by the intervening cold neutral intergalactic medium (IGM) and collapsed structures. Although the existence of high-z radio loud sources has not been confirmed yet, SKA-low would be the instrument of choice to find such sources as they are expected to have spectra steeper than their lower-z counterparts. Since the strongest absorption features arise from small scale structures (few tens of physical kpc, or even lower), the 21cm forest can probe the HI density power spectrum on small scales not amenable to measurements by any other means. Also, it can be a unique probe of the heating process and the thermal history of the early universe, as the signal is strongly dependent on the IGM temperature. Here we show what SKA1-low could do in terms of detecting the 21cm forest in the redshift range z = 7.5-15. \\ ( http://arxiv.org/abs/1501.04425 , 117kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04459 Date: Mon, 19 Jan 2015 11:42:46 GMT (1333kb) Title: The physics of Reionization: processes relevant for SKA observations Authors: Benoit Semelin and Ilian Iliev Categories: astro-ph.CO Comments: 10 pages, 1 figure. Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The local intensity of the 21 cm signal emitted during the Epoch of Reionization that will be mapped by the SKA is modulated by the amount of neutral hydrogen. Consequently, understanding the process of reionization of the intergalactic medium (IGM) is crucial for predicting and interpreting the upcoming observations. After presenting the basic physics and most meaningful quantities pertaining to the process of reionization, we will review recent progress in our understanding of the production and escape of ionizing photons in primordial galaxies and of their absorption in the IGM especially in so-called minihalos and Lyman Limit Systems. \\ ( http://arxiv.org/abs/1501.04459 , 1333kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04141 Date: Sat, 17 Jan 2015 01:40:40 GMT (2169kb) Title: Probing First Galaxies and Their Impact on the Intergalactic Medium through the 21-cm Observation of the Cosmic Dawn with the SKA Authors: Kyungjin Ahn, Andrei Mesenger, Marcelo A. Alvarez, Xuelei Chen Categories: astro-ph.GA astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ We present an overview of the theory of high-redshift star and X-ray source formation, and how they affect the 21-cm background. Primary focus is given to Lyman alpha pumping and X-ray heating mechanisms at cosmic dawn, opening a new observational window for high-redshift astrophysics by generating sizable fluctuations in the 21-cm background. We describe observational prospects for power spectrum analysis and 3D tomography (imaging) of the signature of these early astrophysical sources by SKA1-LOW and SKA2. \\ ( http://arxiv.org/abs/1501.04141 , 2169kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04340 Date: Sun, 18 Jan 2015 19:52:48 GMT (111kb,D) Title: All-sky signals from recombination to reionization with the SKA Authors: Ravi Subrahmanyan, N. Udaya Shankar, Jonathan Pritchard, Harish K. Vedantham Categories: astro-ph.IM astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ Cosmic evolution in the hydrogen content of the Universe through recombination and up to the end of reionization is expected to be revealed as subtle spectral features in the uniform extragalactic cosmic radio background. The redshift evolution in the excitation temperature of the 21-cm spin flip transition of neutral hydrogen appears as redshifted emission and absorption against the cosmic microwave background. The precise signature of the spectral trace from cosmic dawn and the epoch of reionization are dependent on the spectral radiance, abundance and distribution of the first bound systems of stars and early galaxies, which govern the evolution in the spin-flip level populations. Redshifted 21 cm from these epochs when the spin temperature deviates from the temperature of the ambient relic cosmic microwave background results in an all-sky spectral structure in the 40-200 MHz range, almost wholly within the band of SKA-Low. Another spectral structure from gas evolution is redshifted recombination lines from epoch of recombination of hydrogen and helium; the weak all-sky spectral structure arising from this event is best detected at the upper end of the 350-3050 MHz band of SKA-mid. Total power spectra of SKA interferometer elements form the measurement set for these faint signals from recombination and reionization; the inter-element interferometer visibilities form a calibration set. The challenge is in precision polarimetric calibration of the element spectral response and solving for additives and unwanted confusing leakages of sky angular structure modes into spectral modes. Herein we discuss observing methods and design requirements that make possible these all-sky SKA measurements of the cosmic evolution of hydrogen. \\ ( http://arxiv.org/abs/1501.04340 , 111kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04429 Date: Mon, 19 Jan 2015 09:28:28 GMT (657kb,D) Title: Cosmic Dawn and Epoch of Reionization Foreground Removal with the SKA Authors: Emma Chapman and Anna Bonaldi and Geraint Harker and Vibor Jeli\'c and Filipe B. Abdalla and Gianni Bernardi and J\'er\^ome Bobin and Fred Dulwich and Benjamin Mort and Mario Santos and Jean-Luc Starck Categories: astro-ph.IM astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ The exceptional sensitivity of the SKA will allow observations of the Cosmic Dawn and Epoch of Reionization (CD/EoR) in unprecedented detail, both spectrally and spatially. This wealth of information is buried under Galactic and extragalactic foregrounds, which must be removed accurately and precisely in order to reveal the cosmological signal. This problem has been addressed already for the previous generation of radio telescopes, but the application to SKA is different in many aspects. In this chapter we summarise the contributions to the field of foreground removal in the context of high redshift and high sensitivity 21-cm measurements. We use a state-of-the-art simulation of the SKA Phase 1 observations complete with cosmological signal, foregrounds and frequency-dependent instrumental effects to test both parametric and non-parametric foreground removal methods. We compare the recovered cosmological signal using several different statistics and explore one of the most exciting possibilities with the SKA --- imaging of the ionized bubbles. We find that with current methods it is possible to remove the foregrounds with great accuracy and to get impressive power spectra and images of the cosmological signal. The frequency-dependent PSF of the instrument complicates this recovery, so we resort to splitting the observation bandwidth into smaller segments, each of a common resolution. If the foregrounds are allowed a random variation from the smooth power law along the line of sight, methods exploiting the smoothness of foregrounds or a parametrization of their behaviour are challenged much more than non-parametric ones. However, we show that correction techniques can be implemented to restore the performances of parametric approaches, as long as the first-order approximation of a power law stands. \\ ( http://arxiv.org/abs/1501.04429 , 657kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04654 Date: Mon, 19 Jan 2015 21:43:34 GMT (119kb,D) Title: Synergy of CO/[CII]/Ly$\alpha$ Line Intensity Mapping with the SKA Authors: Tzu-Ching Chang, Yan Gong, Mario Santos, Marta Silva, James Aguirre, Olivier Dor\'e, Jonathan Pritchard, for the SKA EoR/CD SWG Categories: astro-ph.CO Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics Synergy of CO/[CII]/Ly$\alpha$ Line Intensity Mapping with the SKAwith the Square Kilometre Array', to appear in 2015 \\ We present the science enabled by cross-correlations of the SKA1-LOW 21-cm EoR surveys with other line mapping programs. In particular, we identify and investigate potential synergies with planned programs, such as the line intensity mapping of redshifted CO rotational lines, [CII] and Ly-$\alpha$ emissions during reionization. We briefly describe how these tracers of the star-formation rate at $z \sim 8$ can be modeled jointly before forecasting their auto- and cross-power spectra measurements with the nominal 21cm EoR survey. The use of multiple line tracers would be invaluable to validate and enrich our understanding of the EoR. \\ ( http://arxiv.org/abs/1501.04654 , 119kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04820 Date: Tue, 20 Jan 2015 14:26:50 GMT (870kb,D) Title: Exploring AGN Activity over Cosmic Time with the SKA Authors: Vernesa Smolcic, Paolo Padovani, Jacinta Delhaize, Isabella Prandoni, Nicholas Seymour, Matt Jarvis, Jose Afonso, Manuela Magliocchetti, Minh Huynh, Mattia Vaccari, Alexander Karim Categories: astro-ph.GA Comments: 17 pages, 7 figures, to appear as part of 'Continuum Science' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)' \\ In this Chapter we present the motivation for undertaking both a wide and deep survey with the SKA in the context of studying AGN activity across cosmic time. With an rms down to 1 $\mu$Jy/beam at 1 GHz over 1,000 - 5,000 deg$^2$ in 1 year (wide tier band 1/2) and an rms down to 200 nJy/beam over 10 - 30 deg$^2$ in 2000 hours (deep tier band 1/2), these surveys will directly detect faint radio-loud and radio-quiet AGN (down to a 1 GHz radio luminosity of about $2\times10^{23}$ W/Hz at $z=6$). For the first time, this will enable us to conduct detailed studies of the cosmic evolution of radio AGN activity to the cosmic dawn ($z\gtrsim6$), covering all environmental densities. \\ ( http://arxiv.org/abs/1501.04820 , 870kb) ------------------------------------------------------------------------------ \\ arXiv:1501.04627 (*cross-listing*) Date: Mon, 19 Jan 2015 21:00:12 GMT (173kb) Title: Time domain studies of Active Galactic Nuclei with the Square Kilometre Array Authors: Hayley Bignall, Steve Croft, Talvikki Hovatta, Jun Yi Koay, Joseph Lazio, Jean-Pierre Macquart, and Cormac Reynolds Categories: astro-ph.HE astro-ph.GA Comments: To be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14) \\ Variability of radio-emitting active galactic nuclei can be used to probe both intrinsic variations arising from shocks, flares, and other changes in emission from regions surrounding the central supermassive black hole, as well as extrinsic variations due to scattering by structures in our own Galaxy. Such interstellar scattering also probes the structure of the emitting regions, with microarcsecond resolution. Current studies have necessarily been limited to either small numbers of objects monitored over long periods of time, or large numbers of objects but with poor time sampling. The dramatic increase in survey speed engendered by the Square Kilometre Array will enable precision synoptic monitoring studies of hundreds of thousands of sources with a cadence of days or less. Statistics of variability, in particular concurrent observations at multiple radio frequencies and in other bands of the electromagnetic spectrum, will probe accretion physics over a wide range of AGN classes, luminosities, and orientations, as well as enabling a detailed understanding of the structures responsible for radio wave scattering in the Galactic interstellar medium. \\ ( http://arxiv.org/abs/1501.04627 , 173kb) ------------------------------------------------------------------------------ \\ arXiv:1501.05367 Date: Thu, 22 Jan 2015 01:51:42 GMT (4477kb) Title: Delivering SKA Science Authors: Peter Quinn, Tim Axelrod, Ian Bird, Richard Dodson, Alex Szalay, Andreas Wicenec Categories: astro-ph.IM cs.DC Comments: 27 pages, 14 figures, Conference: Advancing Astrophysics with the Square Kilometre Array June 8-13, 2014 Giardini Naxos, Italy \\ The SKA will be capable of producing a stream of science data products that are Exa-scale in terms of their storage and processing requirements. This Google-scale enterprise is attracting considerable international interest and excitement from within the industrial and academic communities. In this chapter we examine the data flow, storage and processing requirements of a number of key SKA survey science projects to be executed on the baseline SKA1 configuration. Based on a set of conservative assumptions about trends for HPC and storage costs, and the data flow process within the SKA Observatory, it is apparent that survey projects of the scale proposed will potentially drive construction and operations costs beyond the current anticipated SKA1 budget. This implies a sharing of the resources and costs to deliver SKA science between the community and what is contained within the SKA Observatory. A similar situation was apparent to the designers of the LHC more than 10 years ago. We propose that it is time for the SKA project and community to consider the effort and process needed to design and implement a distributed SKA science data system that leans on the lessons of other projects and looks to recent developments in Cloud technologies to ensure an affordable, effective and global achievement of SKA science goals. \\ ( http://arxiv.org/abs/1501.05367 , 4477kb) ------------------------------------------------------------------------------ \\ arXiv:1501.05591 (*cross-listing*) Date: Thu, 22 Jan 2015 18:25:53 GMT (176kb,D) Title: Multi-wavelength, Multi-Messenger Pulsar Science in the SKA Era Authors: John Antoniadis, Lucas Guillemot, Andrea Possenti, Slavko Bogdanov, Joseph D. Gelfand, Michael Kramer, Roberto Mignani, Benjamin Stappers, Pablo Torne Categories: astro-ph.HE astro-ph.IM astro-ph.SR gr-qc nucl-ex Comments: 14 pages, 1 figure, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)157 \\ The Square Kilometre Array (SKA) is an integral part of the next-generation observatories that will survey the Universe across the electromagnetic spectrum, and beyond, revolutionizing our view of fundamental physics, astrophysics and cosmology. Owing to their extreme nature and clock-like properties, pulsars discovered and monitored by SKA will enable a broad range of scientific endeavour and play a key role in this quest. This chapter summarizes the pulsar-related science goals that will be reached with coordinated efforts among SKA and other next-generation astronomical facilities. \\ ( http://arxiv.org/abs/1501.05591 , 176kb) ------------------------------------------------------------------------------ \\ arXiv:1501.05367 Date: Thu, 22 Jan 2015 01:51:42 GMT (4477kb) Title: Delivering SKA Science Authors: Peter Quinn, Tim Axelrod, Ian Bird, Richard Dodson, Alex Szalay, Andreas Wicenec Categories: astro-ph.IM cs.DC Comments: 27 pages, 14 figures, Conference: Advancing Astrophysics with the Square Kilometre Array June 8-13, 2014 Giardini Naxos, Italy \\ The SKA will be capable of producing a stream of science data products that are Exa-scale in terms of their storage and processing requirements. This Google-scale enterprise is attracting considerable international interest and excitement from within the industrial and academic communities. In this chapter we examine the data flow, storage and processing requirements of a number of key SKA survey science projects to be executed on the baseline SKA1 configuration. Based on a set of conservative assumptions about trends for HPC and storage costs, and the data flow process within the SKA Observatory, it is apparent that survey projects of the scale proposed will potentially drive construction and operations costs beyond the current anticipated SKA1 budget. This implies a sharing of the resources and costs to deliver SKA science between the community and what is contained within the SKA Observatory. A similar situation was apparent to the designers of the LHC more than 10 years ago. We propose that it is time for the SKA project and community to consider the effort and process needed to design and implement a distributed SKA science data system that leans on the lessons of other projects and looks to recent developments in Cloud technologies to ensure an affordable, effective and global achievement of SKA science goals. \\ ( http://arxiv.org/abs/1501.05367 , 4477kb) ------------------------------------------------------------------------------ \\ arXiv:1501.05591 (*cross-listing*) Date: Thu, 22 Jan 2015 18:25:53 GMT (176kb,D) Title: Multi-wavelength, Multi-Messenger Pulsar Science in the SKA Era Authors: John Antoniadis, Lucas Guillemot, Andrea Possenti, Slavko Bogdanov, Joseph D. Gelfand, Michael Kramer, Roberto Mignani, Benjamin Stappers, Pablo Torne Categories: astro-ph.HE astro-ph.IM astro-ph.SR gr-qc nucl-ex Comments: 14 pages, 1 figure, to be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14)157 \\ The Square Kilometre Array (SKA) is an integral part of the next-generation observatories that will survey the Universe across the electromagnetic spectrum, and beyond, revolutionizing our view of fundamental physics, astrophysics and cosmology. Owing to their extreme nature and clock-like properties, pulsars discovered and monitored by SKA will enable a broad range of scientific endeavour and play a key role in this quest. This chapter summarizes the pulsar-related science goals that will be reached with coordinated efforts among SKA and other next-generation astronomical facilities. \\ ( http://arxiv.org/abs/1501.05591 , 176kb) ------------------------------------------------------------------------------ \\ arXiv:1501.05643 Date: Wed, 21 Jan 2015 21:02:34 GMT (255kb,D) Title: Stacking of SKA data: comparing uv-plane and image-plane stacking Authors: K.K. Knudsen, L. Lindroos, W. Vlemmings, J. Conway, I. Marti-Vidal Categories: astro-ph.IM astro-ph.CO astro-ph.GA Comments: Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015 \\ Stacking as a tool for studying objects that are not individually detected is becoming popular even for radio interferometric data, and will be widely used in the SKA era. Stacking is typically done using imaged data rather than directly using the visibilities (the uv-data). We have investigated and developed a novel algorithm to do stacking using the uv-data. We have performed exten- sive simulations comparing to image-stacking, and summarize the results of these simulations. Furthermore, we disuss the implications in light of the vast data volume produced by the SKA. Having access to the uv-stacked data provides a great advantage, as it allows the possibility to properly analyse the result with respect to calibration artifacts as well as source properties such as size. For SKA the main challenge lies in archiving the uv-data. For purposes of robust stacking analysis, it would be strongly desirable to either keep the calibrated uv-data at least in an aver- age form, or implement a stacking queue where stacking positions could be provided prior to the observations and the uv-stacking is done almost in real time. \\ ( http://arxiv.org/abs/1501.05643 , 255kb) ------------------------------------------------------------------------------ \\ arXiv:1501.07535 (*cross-listing*) Date: Mon, 19 Jan 2015 21:26:05 GMT (486kb) Title: Fast Transients at Cosmological Distances with the SKA Authors: J.-P. Macquart, E. Keane, K. Grainge, M. McQuinn, R.P. Fender, J. Hessels, A. Deller, R. Bhat, R. Breton, S. Chatterjee, C. Law, D. Lorimer, E.O. Ofek, M. Pietka, L. Spitler, B. Stappers, C. Trott Categories: astro-ph.HE astro-ph.CO Comments: To be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14) \\ Impulsive radio bursts that are detectable across cosmological distances constitute extremely powerful probes of the ionized Inter-Galactic Medium (IGM), intergalactic magnetic fields, and the properties of space-time itself. Their dispersion measures (DMs) will enable us to detect the "missing" baryons in the low-redshift Universe and make the first measurements of the mean galaxy halo profile, a key parameter in models of galaxy formation and feedback. Impulsive bursts can be used as cosmic rulers at redshifts exceeding 2, and constrain the dark energy equation-of-state parameter, $w(z)$ at redshifts beyond those readily accessible by Type Ia SNe. Both of these goals are realisable with a sample of $\sim 10^4$ fast radio bursts (FRBs) whose positions are localized to within one arcsecond, sufficient to obtain host galaxy redshifts via optical follow-up. It is also hypothesised that gravitational wave events may emit coherent emission at frequencies probed by SKA1-LOW, and the localization of such events at cosmological distances would enable their use as cosmological standard sirens. To perform this science, such bursts must be localized to their specific host galaxies so that their redshifts may be obtained and compared against their dispersion measures, rotation measures, and scattering properties. The SKA can achieve this with a design that has a wide field-of-view, a substantial fraction of its collecting area in a compact configuration (80\% within a 3\,km radius), and a capacity to attach high-time-resolution instrumentation to its signal path. \\ ( http://arxiv.org/abs/1501.07535 , 486kb) ------------------------------------------------------------------------------ \\ arXiv:1501.07535 (*cross-listing*) Date: Mon, 19 Jan 2015 21:26:05 GMT (486kb) Title: Fast Transients at Cosmological Distances with the SKA Authors: J.-P. Macquart, E. Keane, K. Grainge, M. McQuinn, R.P. Fender, J. Hessels, A. Deller, R. Bhat, R. Breton, S. Chatterjee, C. Law, D. Lorimer, E.O. Ofek, M. Pietka, L. Spitler, B. Stappers, C. Trott Categories: astro-ph.HE astro-ph.CO Comments: To be published in: "Advancing Astrophysics with the Square Kilometre Array", Proceedings of Science, PoS(AASKA14) \\ Impulsive radio bursts that are detectable across cosmological distances constitute extremely powerful probes of the ionized Inter-Galactic Medium (IGM), intergalactic magnetic fields, and the properties of space-time itself. Their dispersion measures (DMs) will enable us to detect the "missing" baryons in the low-redshift Universe and make the first measurements of the mean galaxy halo profile, a key parameter in models of galaxy formation and feedback. Impulsive bursts can be used as cosmic rulers at redshifts exceeding 2, and constrain the dark energy equation-of-state parameter, $w(z)$ at redshifts beyond those readily accessible by Type Ia SNe. Both of these goals are realisable with a sample of $\sim 10^4$ fast radio bursts (FRBs) whose positions are localized to within one arcsecond, sufficient to obtain host galaxy redshifts via optical follow-up. It is also hypothesised that gravitational wave events may emit coherent emission at frequencies probed by SKA1-LOW, and the localization of such events at cosmological distances would enable their use as cosmological standard sirens. To perform this science, such bursts must be localized to their specific host galaxies so that their redshifts may be obtained and compared against their dispersion measures, rotation measures, and scattering properties. The SKA can achieve this with a design that has a wide field-of-view, a substantial fraction of its collecting area in a compact configuration (80\% within a 3\,km radius), and a capacity to attach high-time-resolution instrumentation to its signal path. \\ ( http://arxiv.org/abs/1501.07535 , 486kb)