We present a sky simulation of the atomic HI emission line and the first ten CO rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500/h Mpc, hence the actual field-of-view depends on the (user-defined) maximal redshift zmax; e.g. for zmax=10, the field of view yields ~4x4 sqdeg. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the HI and CO emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 10^8 Msun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Lambda-cold dark matter (LCDM) cosmology. The evolving CDM-distribution was adopted from the Millennium Simulation, an N-body CDM-simulation in a cubic box with a side length of 500/h Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations (BAOs) in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such the SKA, the LMT, and ALMA. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz-analyzes for peak flux density limited and total flux limited surveys of HI and CO. A key prediction is that HI will be harder to detect at redshifts z>2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models.
We forecast the abilities of the Atacama Large Millimeter/submillimeter Array (ALMA) and the Square Kilometer Array (SKA) to detect CO and HI emission lines in galaxies at redshift z=3. A particular focus is set on Milky Way (MW) progenitors at z=3 for their detection within 24 h constitutes a key science goal of ALMA. The analysis relies on a semi-analytic model, which permits the construction of a MW progenitor sample by backtracking the cosmic history of all simulated present-day galaxies similar to the real MW. Results: (i) ALMA can best observe a MW at z=3 by looking at CO(3-2) emission. …
In these proceedings I discuss various extragalactic surveys which will be undertaken over the next few years and which will be complementary to any HI and/or continuum surveys with the SKA-precursor telescopes. I concentrate on the near-infrared public surveys which will be undertaken with the Visible and Infrared Survey Telscope for Astronomy (VISTA), and in particular the VISTA Deep Extragalactic Observations (VIDEO) survey which will provide the ideal data set to combine with any deep SKA-precursor observations of the extragalactic sky. After highlighting the links that the SKA precursors …
We present statistics of 133 faint 1.2-mm continuum sources detected in about 120 deep ALMA pointing data that include all the archival deep data available by 2015 June. We derive number counts of 1.2 mm continuum sources down to 0.02 mJy partly with the assistance of gravitational lensing, and find that the total integrated 1.2 mm flux of the securely identified sources is 22.9^(+6.7)_(-5.6) Jy deg^(-2) that corresponds to 104^(+31)_(-25) % of the extragalactic background light (EBL) measured by COBE observations. These results suggest that the major 1.2 mm EBL contributors are sources with 0…
We present results from simulations of the extragalactic polarized sky at 1.4 GHz. As the basis for our polarization models, we use a semi-empirical simulation of the extragalactic total intensity (Stokes I) continuum sky developed at the University of Oxford (http://scubed.physics.ox.ac.uk) under the European SKA Design Study (SKADS) initiative, and polarization distributions derived from analysis of polarization observations. By considering a luminosity dependence for the polarization of AGN, we are able to fit the 1.4 GHz polarized source counts derived from the NVSS and the DRAO ELAIS N1 d…
We present a theoretical study of the deuterated species detectability in various types of extragalactic star-forming regions based on our predictions of chemical abundances. This work is motivated by the past and current attempts at observing deuterated species in external galaxies such as NGC~253, IC~342 and the LMC. Here, we investigate the influence of the density, the temperature, the FUV radiation field, the cosmic ray ionisation, and the metallicity on the fractional abundances and D/H abundance ratios of about 20 deuterated species. Without modelling any particular source, we determine…
We report 345 GHz continuum observations of the host galaxies of gamma-ray bursts (GRBs) 021004 and 080607 at z>2 using the Atacama Large Millimeter/Submillimeter Array (ALMA) in Cycle 0. Of the two bursts, GRB021004 is one of the few GRBs that originates in a Lyman limit host, while GRB080607 is classified as a "dark burst" and its host galaxy is a candidate of dusty star forming galaxy at z~3. With an order of magnitude improvement in the sensitivities of the new imaging searches, we detect the host galaxy of GRB080607 with a flux of S_{345} = 0.31+/-0.09 mJy and a corresponding infrared lum…
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…
To exploit synergies between the Herschel Space Observatory and next generation radio facilities, we have extended the semi-empirical extragalactic radio continuum simulation of Wilman et al. (2008) to the mid- and far-infrared. Here we describe the assignment of infrared spectral energy distributions (SEDs) to the star-forming galaxies and active galactic nuclei, using Spitzer 24, 70 and 160 micron and SCUBA 850 micron survey results as the main constraints. Star-forming galaxies dominate the source counts, and a model in which their far-infrared-radio correlation and infrared SED assignment …
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…
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 sur…
Rotation measure (RM) grids of extragalactic radio sources have been widely used for studying cosmic magnetism. But their potential for exploring the intergalactic magnetic field (IGMF) in filaments of galaxies is unclear, since other Faraday-rotation media such as the radio source itself, intervening galaxies, and the interstellar medium of our Galaxy are all significant contributors. We study statistical techniques for discriminating the Faraday rotation of filaments from other sources of Faraday rotation in future large-scale surveys of radio polarization. We consider a 30 degree times 30 d…
The MIGHTEE large survey project will survey four of the most well-studied extragalactic deep fields, totalling 20 square degrees to $μ$Jy sensitivity at Giga-Hertz frequencies, as well as an ultra-deep image of a single ~1 square degree MeerKAT pointing. The observations will provide radio continuum, spectral line and polarisation information. As such, MIGHTEE, along with the excellent multi-wavelength data already available in these deep fields, will allow a range of science to be achieved. Specifically, MIGHTEE is designed to significantly enhance our understanding of, (i) the evolution of …
We present the Tiered Radio Extragalactic Continuum Simulation (T-RECS): a new simulation of the radio sky in continuum, over the 150 MHz-20 GHz range. T-RECS models two main populations of radio galaxies: Active Galactic Nuclei (AGNs) and Star-Forming Galaxies (SFGs), and corresponding sub-populations. Our model also includes polarized emission over the full frequency range, which has been characterised statistically for each population using the available information. We model the clustering properties in terms of probability distributions of hosting halo masses, and use lightcones extracted…
SKA-Low simulations for a cosmic dawn/epoch of reionisation deep field
SKA Observatory（SKA天文台）；Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester（曼彻斯特大学物理与天文学学院乔德雷尔银行天体物理学中心）；Department of Physics and Astronomy, University of Pennsylvania（宾夕法尼亚大学物理与天文学系）；LUX, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université（巴黎天文台卢克斯实验室，PSL研究大学，法国国家科学研究中心，索邦大学）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris（巴黎高等师范学校物理实验室，PSL大学，法国国家科学研究中心，索邦大学，巴黎大学）；International Centre for Radio Astronomy Research, Curtin University（科廷大学国际射电天文研究中心）；ARC Centre of Excellence for All-Sky Astrophysics in 3D（ARC三维全天体物理学卓越中心）
We know that magnetic fields are pervasive across all scales in the Universe and over all of cosmic time and yet our understanding of many of the properties of magnetic fields is still limited. We do not yet know when, where or how the first magnetic fields in the Universe were formed, nor do we fully understand their role in fundamental processes such as galaxy formation or cosmic ray acceleration or how they influence the evolution of astrophysical objects. The greatest challenge to addressing these issues has been a lack of deep, broad bandwidth polarimetric data over large areas of the sky…
We investigate the potential of the Square Kilometre Array (SKA) for measuring the magnetic fields in clusters of galaxies via Faraday rotation of background polarised sources. [...] We find that about 10 per cent of the sky is covered by a significant extragalactic Faraday screen. Most of it has rotation measures between 10 and 100 rad/m/m. We argue that the cluster centres should have up to about 5000 rad/m/m. We show that the proposed mid frequency aperture array of the SKA as well as the lowest band of the SKA dish array are well suited to make measurements for most of these rotation measu…
Measurements of the cosmic far-infrared background (CIB) indicate that emission from many extragalactic phenomena, including star formation and black hole accretion, in the Universe can be obscured by dust. Resolving the CIB to study the population of galaxies in which this activity takes place is a major goal of submillimetre astronomy. Here, we present interferometric 650$μ$m submillimetre number counts. Using the Band 8 data from the ALMACAL survey, we have analysed 81 ALMA calibrator fields together covering a total area of 5.5~arcmin$^2$. The typical central rms in these fields is $\sim 1…
The recent availability of wideband receivers and high sensitivity instruments in the mm and submm wavelengths has opened the possibility of studying in detail the chemistry of the interstellar medium in extragalactic objects. Within the central few hundred parsec of galaxies, we find enormous amounts of molecular material fueling a wide variety of highly energetic events observed in starbursts (galaxies undergoing an intense burst of star formation) and active galactic nuclei (AGN, where activity is driven by the accretion of material onto the nuclear black hole). Here it is presented a brief…
The Herschel Multi-tiered Extragalactic Survey (HerMES) has identified large numbers of dusty star-forming galaxies (DSFGs) over a wide range in redshift. A detailed understanding of these DSFGs is hampered by the limited spatial resolution of Herschel. We present 870um 0.45" resolution imaging from the Atacama Large Millimeter/submillimeter Array (ALMA) of 29 HerMES DSFGs with far-infrared (FIR) flux densities in between the brightest of sources found by Herschel and fainter DSFGs found in ground-based sub-millimeter (sub-mm) surveys. We identify 62 sources down to the 5-sigma point-source se…
Measuring radio source counts is critical for characterizing new extragalactic populations, brings a wealth of science within reach and will inform forecasts for SKA and its pathfinders. Yet there is currently great debate (and few measurements) about the behaviour of the 1.4-GHz counts in the microJy regime. One way to push the counts to these levels is via 'stacking', the covariance of a map with a catalogue at higher resolution and (often) a different wavelength. For the first time, we cast stacking in a fully bayesian framework, applying it to (i) the SKADS simulation and (ii) VLA data sta…
We present the statistics of faint submillimeter/millimeter galaxies (SMGs) and serendipitous detections of a submillimeter/millimeter line emitter (SLE) with no multi-wavelength continuum counterpart revealed by the deep ALMA observations. We identify faint SMGs with flux densities of 0.1-1.0 mJy in the deep Band 6 and Band 7 maps of 10 independent fields that reduce cosmic variance effects. The differential number counts at 1.2 mm are found to increase with decreasing flux density down to 0.1 mJy. Our number counts indicate that the faint (0.1-1.0 mJy, or SFR_IR ~ 30-300 Msun/yr) SMGs contri…
Despite their relative sparseness, during the recent years it has become more and more clear that extragalactic radio sources (both AGN and star-forming galaxies) constitute an extremely interesting mix of populations, not only because of their intrinsic value, but also for their fundamental role in shaping our Universe the way we see it today. Indeed, radio-active AGN are now thought to be the main players involved in the evolution of massive galaxies and clusters. At the same time, thanks to the possibility of being observed up to very high redshifts, radio galaxies can also provide crucial …
The AKARI Deep Field South (ADF-S) is a large extragalactic survey field that is covered by multiple instruments, from optical to far-IR and radio. I summarise recent results in this and related fields prompted by the release of the Herschel far-IR/submm images, including studies of cold dust in nearby galaxies, the identification of strongly lensed distant galaxies, and the use of colour selection to find candidate very high redshift sources. I conclude that the potential for significant new results from the ADF-S is very great. The addition of new wavelength bands in the future, eg. from Euc…
We exploit the continuity equation approach and the `main sequence' star-formation timescales to show that the observed high abundance of galaxies with stellar masses > a few 10^10 M_sun at redshift z>4 implies the existence of a galaxy population featuring large star formation rates (SFRs) > 10^2 M_sun/yr in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z<3 in the far-IR band by the Herschel space observatory. We work out specific predictions for the evolution of the corresponding stellar ma…
The ASKAP Variables and Slow Transients (VAST) Extragalactic Survey - Data Release 1
The University of Sydney（悉尼大学）；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；Australia Telescope National Facility, CSIRO Space and Astronomy（澳大利亚望远镜国家设施，CSIRO空间与天文学部）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）；The Hebrew University of Jerusalem（耶路撒冷希伯来大学）；University of Toronto（多伦多大学）
I present simple but robust estimates of the types of sources making up the faint, sub-microJy radio sky. These include, not surprisingly, star-forming galaxies and radio-quiet AGN but also two "new" populations, that is low radio power ellipticals and dwarf galaxies, the latter likely constituting the most numerous component of the radio sky. I then estimate for the first time the X-ray, optical, and mid-infrared fluxes these objects are likely to have, which are very important for source identification and the synergy between the upcoming SKA and its various pathfinders with future missions …
We study the challenges to detect the cosmic web at radio wavelengths with state-of-the-art cosmological simulations of extragalactic magnetic fields. The incoming generation of radio surveys operating at low frequency, like LOFAR, SKA-LOW and MWA will have the best chance to detect the large-scale, low surface brightness emission from the shocked cosmic web. The detected radio emission will enable to constrain the average magnetisation level of the gas in filaments and the acceleration efficiency of electrons by strong shocks. In case of detections, through statistical modelling (e.g. correla…
