An Ultradeep Multiband VLA Survey of the Faint Radio Sky (COSMOS-XS): Source Catalog and Number Counts
D. van der Vlugt, Hiddo Algera, Jacqueline Hodge, Mladen Novak, J. F. Radcliffe, Dominik A. Riechers, H. J. A. Röttgering, V. Smolčić, Fabian Walter
Abstract
Abstract We present ultradeep, matched-resolution Karl G. Jansky Very Large Array observations at 10 and 3 GHz in the COSMOS field: the COSMOS-XS survey. The final 10 and 3 GHz images cover ∼16 and and reach median rms values at the phase center of 0.41 and 0.53 μ Jy beam −1 , respectively. Both images have an angular resolution of ∼20. To account for the spectral shape and resolution variations across the broad bands, we image all data with a multiscale, multifrequency synthesis algorithm. We present source catalogs for the 10 and 3 GHz image with 91 and 1498 sources, respectively, above a peak brightness threshold of 5 σ . We present source counts with completeness corrections included that are computed via Monte Carlo simulations. Our corrected counts at 3 GHz are consistent within the uncertainties with other results at 3 and 1.4 GHz but extend to fainter flux densities than previous direct detections. The 3 GHz number counts exceed the counts predicted by the semiempirical simulations developed in the framework of the SKA Simulated Skies project, consistent with previous P ( D ) analyses. Our source counts suggest a steeper luminosity function evolution for faint star-forming sources. The semiempirical Tiered Radio Extragalactic Continuum Simulation predicts this steeper evolution and is in better agreement with our results at 10 and 3 GHz within the expected variations from cosmic variance. In summary, the multiband, matched-resolution COSMOS-XS survey in the COSMOS field provides a high-resolution view of the ultrafaint radio sky that can help guide next-generation radio facilities.