The VLA‐COSMOS 3 GHz Large Project: Cosmic star formation history since z similar to 5

We make use of the deep Karl G. Jansky Very Large Array (VLA) COSMOS radio observations at 3 GHz to infer radio luminosity functions of star‐forming galaxies up to redshifts of z similar to 5 based on approximately 6000 detections with reliable optical counterparts. This is currently the largest radio‐selected sample available out to z similar to 5 across an area of 2 square degrees with a sensitivity of rms approximate to 2.3 mu Jy beam(‐1). By fixing the faint and bright end shape of the radio luminosity function to the local values, we find a strong redshift trend that can be fitted with a pure luminosity evolution L‐1.4 (GHz) proportional to /(1 + z)((3.16 +/‐ 0.2)‐(0.32 +/‐ 0.07)z). We estimate star formation rates (SFRs) from our radio luminosities using an infrared (IR)‐radio correlation that is redshift dependent. By integrating the parametric fits of the evolved luminosity function we calculate the cosmic SFR density (SFRD) history since z similar to 5. Our data suggest that the SFRD history peaks between 2 1000 M fi yr 1) contribute an additional less than or similar to 2% in the entire observed redshift range. We find evidence of a potential underestimation of SFRD based on ultraviolet (UV) rest‐frame observations of Lyman break galaxies at high redshifts (z greater than or similar to 4) on the order of 15‐20%, owing to appreciable star formation in highly dust‐obscured galaxies, which might remain undetected in such UV observations.