Black hole mass growth across cosmic time; Insights from the VLA-COSMOS survey
Radio-mode AGN feedback is a regular ingredient in cosmological models. It is considered to be a key feedback mechanism at work in the latest phases of massive galaxy formation, and controlling the galaxy’s stellar mass build-up. Yet observationally it is still poorly understood. Over the past decades our understanding of radio AGN was significantly advanced by panchromatic look-back surveys. The VLA-COSMOS 3 GHz Large Project is based on 384 hours of observations with the upgraded, Karl G. Jansky Very Large Array) at 3 GHz (10 cm) toward the two square degree COSMOS field. The survey, reaching a median rms of 2.3 uJy/beam over the two square degrees at an angular resolution of 0.75’’, contains 10,830 radio sources down to 5 times the rms. It simultaneously provides the largest and deepest radio continuum survey at such angular resolution to date. These radio data, in conjunction with the panchromatic COSMOS data sets, allowed us to study the physical properties, composite nature (i.e., star-formation vs. AGN related contributions to the total radio emission of the sources), and cosmic evolution of radio AGN out to a redshift of about 6, which can directly be linked to the radio-mode feedback, as postulated in cosmological models.