Living with a Monster: Impact of Negative AGN Feedback on the ISM in Radio Galaxies

We present observational constraints on how AGN may regulate the thermal and dynamical state of the interstellar medium in radio galaxies at low and high redshift, and thus star formation and galaxy growth. Radio galaxies at z∼2 reveal energetic, extended outflows of few ×1010 M⊙ of warm ionized gas with kinetic energies near the binding energy of a massive galaxy, and a remarkable deficit in cold molecular gas. This suggests that powerful AGN feedback may terminate the active phase of growth of massive galaxies as postulated by models of galaxy evolution.On the example of a nearby radio galaxy we investigate how the AGN may affect the cold/warm ISM. 3C326 N at z = 0.1 is rich in molecular gas but the Schmidt‐Kennicutt diagram suggests a much lower star‐formation efficiency than in ‘normal’ galaxies. Most of the molecular gas is warm and appears heated by shocks on timescales of few ×104 yrs, shorter than the free‐fall time of molecular clouds. We find a fast outflow of warm neutral gas which cannot be dr...