Radio and millimeter continuum surveys and their astrophysical implications

Abstract

We review the statistical properties of the main populations of radio sources, as emerging from radio and millimeter sky surveys. Recent determinations of local luminosity functions are presented and compared with earlier estimates still in widespread use. A number of unresolved issues are discussed. These include: the (possibly luminositydependent) decline of source space densities at high redshifts; the possible dichotomies between evolutionary properties of low-versus high-luminosity and of flat-versus steepspectrum AGN-powered radio sources; and the nature of sources accounting for the upturn of source counts at sub-mJy levels. It is shown that straightforward extrapolations of evolutionary models, accounting for both the far-IR counts and redshift distributions of star-forming galaxies, match the radio source counts at flux-density levels of tens of µJy remarkably well. We consider the statistical properties of rare but physically very interesting classes of sources, such as GHz Peak Spectrum and ADAF/ADIOS sources, and radio afterglows of γ-ray bursts. We also discuss the exploitation of largearea radio surveys to investigate large scale structure through studies of clustering and the Integrated Sachs-Wolfe effect. Finally we briefly describe the potential of the new and forthcoming generations of radio telescopes. A compendium of source counts at different frequencies is given in an appendix.

Planck2013 results. XVII. Gravitational lensing by large-scale structure

“…Physically, the amplitudes of our source corrections are reasonable; at 143 GHz we measurê S 4 143 = (1.3±0.6)×10 −12 µK 4 . From the radio point-source model of De Zotti et al (2010), this corresponds to an effective flux cut of approximately 150 mJy at this frequency, roughly comparable to that expected for the S /N > 5 cut we make when masking sources in our fiducial analysis (Planck Collaboration XXVIII 2014). The shot noise measured at 217 GHz is lower, as expected given the smaller contribution from radio sources, witĥ S 4 217 = (0.4 ± 0.4) × 10 −12 µK 4 .…”

Planckearly results. XIII. Statistical properties of extragalactic radio sources in thePlanckEarly Release Compact Source Catalogue

“…Assuming a Poisson distribution (clustering effects are reduced to negligible values by the very broad luminosity function of radio sources, e.g., Toffolatti et al 2005;de Zotti et al 2010) and simply scaling As it is apparent, the two values are very close to each other, within the 1σ level calculated for the overall population in the two sky areas considered here, and well inside the 1σ normalized Poisson error bars. We also checked that at flux densities below about 0.9-1.0 Jy statistically more relevant deviations from a uniform distribution begin to appear.…”

Radio Continuum Surveys with Square Kilometre Array Pathfinders

“…Since it is inconsistent with known radio source populations (e.g. De Zotti et al 2010;Padovani 2011), it must, if confirmed, be caused by another population. For example, the radio emission could be caused by dark matter annihilation (Fornengo et al 2011), in which case the emission would trace the dark matter distribution of cluster galaxies, resulting in a scale size of ß arcmin.…”