Active Galactic Nucleus Feedback in an Elliptical Galaxy with the Most
  Updated AGN Physics: Parameter Explorations
  In a previous work, we have proposed a sub-grid model of active galactic
nucleus (AGN) feedback by taking into account the state-of-the-art AGN physics,
and used that model to study the effect of AGN feedback on the evolution of an
isolated elliptical galaxy by performing two dimensional high-resolution (i.e.,
the Bondi radius is well resolved) simulations. In that work, typical values of
model parameters were adopted. In the present work, we extend that study by
exploring the effects of uncertainties of parameter values. Such a study is
also useful for us to understand the respective roles of various components of
the model. These parameters include the mass flux and velocity of AGN wind and
radiative efficiency in both the hot and cold feedback modes, and the initial
black hole (BH) mass. We find that the velocity of AGN wind in the hot mode is
the most important quantity to control the typical accretion rate and
luminosity of AGN, and the mass growth of the BH. The effect of the wind on
star formation is less sensitive. Within the limited parameter range explored
in the current work, a stronger AGN wind suppresses star formation within ~100
pc but enhances star formation beyond this radius, while the star formation
integrated over the evolution time and the whole galaxy roughly remain
unchanged. AGN radiation suppresses the BH accretion in a mild way, but dust is
not considered here. Finally, a smaller initial BH mass results in a more
violent evolution of the BH accretion rate. The corresponding AGN spends more
time in the high-luminosity state and the percentage of BH mass growth is
higher. Our results indicate the robustness of AGN feedback in keeping the
galaxy quenched.
