Clues on black hole feedback from simulated and observed X-ray
  properties of elliptical galaxies
  The centers of elliptical galaxies host supermassive black holes that
significantly affect the surrounding interstellar medium through feedback
resulting from the accretion process. The evolution of this gas and of the
nuclear emission during the galaxies' lifetime has been studied recently with
high-resolution hydrodynamical simulations. These included gas cooling and
heating specific for an average AGN spectral energy distribution, a radiative
efficiency declining at low mass accretion rates, and mechanical coupling
between the hot gas and AGN winds. Here we present a short summary of the
observational properties resulting from the simulations, focussing on 1) the
nuclear luminosity; 2) the global luminosity and temperature of the hot gas; 3)
its temperature profile and X-ray brightness profile. These properties are
compared with those of galaxies of the local universe, pointing out the
successes of the adopted feedback and the needs for new input in the
simulations.
