Stellar and AGN Feedback in Isolated Early-type Galaxies: The Role in RegulatingStar Formation and ISM Properties

How galaxies maintain the inefficiency of star formation with physically self-consistent models is a central problem in understanding galaxy evolution. Although numerous theoretical models have been proposed in recent decades, the debate continues. By means of high-resolution two-dimensional hydrodynamical simulations, we study the three feedback effects (the stellar wind heating, supernova (SN) feedback, and active galactic nucleus (AGN) feedback) in suppressing star formation activities on the evolution of early-type galaxies with different stellar masses. The AGN feedback models are updated from work by Yuan et al. The gas sources arise exclusively from the mass losses of dying low-mass stars for most of our models. We find that SN feedback can keep star formation at a significantly low level for low-mass elliptical galaxies for a cosmological evolution time. For high-mass galaxies, AGN feedback can efficiently offset radiative cooling and thus regulate star formation activity. Such a suppression of star formation is extremely efficient in the inner regions of galaxies. Asymptotic giant branch heating cannot account for this suppression for low- or high-mass galaxies. The X-ray temperature T X and luminosity L X of hot plasma can be in agreement with the observed data with the inclusion of effective feedback processes. These results thus suggest that we can use T X and L X to probe the role of different feedback processes. The inclusion of additional gas sources can cause the mass scale between SN and AGN feedback to dominate in suppressing star formation decrease to an observationally inferred value of a few 1010 M ⊙.