AGN feedback and star formation in ETGs: negative and positive feedback
  AGN feedback from supermassive black holes (SMBHs) at the center of early
type galaxies is commonly invoked as the explanation for the quenching of star
formation in these systems. The situation is complicated by the significant
amount of mass injected in the galaxy by the evolving stellar population over
cosmological times. In absence of feedback, this mass would lead to unobserved
galactic cooling flows, and to SMBHs two orders of magnitude more massive than
observed. By using high-resolution 2D hydrodynamical simulations with radiative
transport and star formation in state-of-the-art galaxy models, we show how the
intermittent AGN feedback is highly structured on spatial and temporal scales,
and how its effects are not only negative (shutting down the recurrent cooling
episodes of the ISM), but also positive, inducing star formation in the inner
regions of the host galaxy.
