Unveiling the physics of radio AGN feedback with LOFAR

The energy injected by the jets of radio-loud active galaxies (radio galaxies and radio-loud quasars) is now widely understood to regulate the cooling of the hot phase of the intergalactic medium and hence to suppress what would otherwise be the runaway growth of the most massive galaxies, giving rise to the galaxy mass function that we observe today (Croton et al. 2006). Many studies of individual systems have shown that radio-loud AGN do indeed heat, lift and mix the hot and warm gas phases (see e.g. McNamara & Nulsen 2012 for a review). However, in order to test that this ‘feedback’ mechanism actually can quantitatively offset cooling across the range of galaxy masses and environments, and to investigate issues such as the stochasticity of AGN heating and how the balance of heating and cooling evolves over cosmic time, unbiased observations of the whole radio AGN population are required. Current and next generation radio instruments can provide these and this is the focus of
our current work and of the present proposal.