Two phase formation of massive elliptical galaxies: the role of AGN feedback

Feedback from active galactic nuclei (AGNs) at the centers of galaxies is believed to play a major role during galaxy formation and evolution of those galaxies and central black holes (BHs). However, in many popular treatments of AGN feedback model some of the most basic requirements, such as the necessity that mass and momentum be conserved have not been imposed, and the inclusion of the presently known and observed feedback processes is often treated selectively. In this talk I will introduce the momentum based mechanical AGN feedback model in a three-dimensional hydrodynamics code, and a suite of cosmological hydrodynamical simulations I use to study the impact of AGN on physical properties of massive elliptical galaxies. I will discuss how AGN feedback plays an important role in making massive galaxies quench their star formation, as well as in making galaxies “bigger” in size. I will describe how the different feedback components affect the two-phase character of the stars ending up in the final galaxies, i.e., stars that are created inside the galaxies themselves (in situ) and those that are created outside and are accreted later on (ex situ).