The Chemo-Dynamical Evolution of Elliptical Galaxies: Pre-heating and   AGN heating
  We study the chemodynamical evolution of elliptical galaxies and their X-ray and optical properties using high-resolution cosmological simulations. Our Tree N-body/SPH code includes a self-consistent treatment of radiative cooling, star formation, supernovae feedback, and chemical enrichment. We present a series of LCDM cosmological simulations which trace the spatial and temporal evolution of abundances of heavy elements in both the stellar and gas components of galaxies. A giant elliptical galaxy formed in one of the simulations is quantitatively compared with the observational data in both the X-ray and optical regime. We implement a treatment of both pre-heating and AGN heating in this simulation, and examine the effect of these processes on elliptical galaxy formation. We find that the adopted pre-heating (T=10^7 K at z=4) is not strong enough to explain the observed X-ray or optical properties. On the other hand, our AGN heating model in which the gas inflow induces the AGN heating is consistent with both the X-ray and optical properties. 
Daisuke Kawata, Brad K. Gibson (Swinburne)