Cosmic evolution of jet-mode AGN feedback: new insights from LOFAR surveys

Active galactic nuclei (AGN) can have a significant effect on their host galaxies by regulating their growth or suppressing star formation (known as AGN feedback). Of particular importance for massive galaxies and clusters are jet-mode AGN which display powerful radio jets and keep galaxies 'red and dead' once quenched. However, the cosmic evolution of these AGN remains poorly constrained at early times. The LOFAR telescope has been undertaking one of the deepest wide-field radio continuum surveys to date: this represents a novel sample to statistically study the evolution of AGN activity and feedback across cosmic time. Using this sample, I will present the first robust measurement of jet-mode AGN feedback out to z ~ 2.5. We discover a new dominant population of jet-mode AGN hosted by star-forming galaxies at high redshifts, that has not been previously observed. The bulk of the radio-mode heating output at earlier times is performed by this new population, which has interesting implications for galaxy quenching. Through comparison with various models, we find that the latest cosmological simulations are unable to match these latest observations.