Active Galactic Nucleus Feedback in an Isolated Elliptical Galaxy: The Effect of Strong Radiative Feedback in the Kinetic Mode

Abstract

Based on two-dimensional high resolution hydrodynamic numerical simulation, we study the mechanical and radiative feedback effects from the central AGN on the cosmological evolution of an isolated elliptical galaxy. Physical processes such as star formation and supernovae are considered. The inner boundary of the simulation domain is carefully chosen so that the fiducial Bondi radius is resolved and the accretion rate of the black hole is determined self-consistently. In analogy to previous works, we assume that the specific angular momentum of the galaxy is low. It is well-known that when the accretion rates are high and low, the central AGNs will be in cold and hot accretion modes, which correspond to the radiative and kinetic feedback modes, respectively. The emitted spectrum from the hot accretion flows is harder than that from the cold accretion flows, which could result in a higher Compton temperature accompanied by a more efficient radiative heating, according to previous theoretical works. Such a difference of the Compton temperature between the two feedback modes, the focus of this study, has been neglected in previous works. Significant differences in the kinetic feedback mode are found as a result of the stronger Compton heating and accretion becomes more chaotic. More importantly, if we constrain models to correctly -2 -predict black hole growth and AGN duty cycle after cosmological evolution, we find that the favored model parameters are constrained: mechanical feedback efficiency diminishes with decreasing luminosity (the maximum efficiency being ≃ 10 −3.5 ) and X-ray Compton temperature increases with decreasing luminosity, although models with fixed mechanical efficiency and Compton temperature can be found that are satisfactory as well. We conclude that radiative feedback in the kinetic mode is much more important than previously thought.

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

“…The light travel time arguments of the source morphological asymmetry require modulation of activity on timescales of 10 few 10 5 6-years for physical scales of 100 kpc-1 Mpc. Hydrodynamical simulations of supermassive black hole temporal evolution (e.g., Novak et al 2011;Gan et al 2014) predict very chaotic accretion, with significant intermittency in accretion rate on a range of timescales, including bursts within a single accretion event (on orders of 10 6 years) and long-term activity intermittency with multiple accretion events (activity with timescales of 10 years 8 , separated by quiescent times of few 10 7 years). Timescales of 10 years 5 for the typical AGN phase (optical and X-ray regimes), and so the timescales of the variability of the supermassive black hole accretion rates, has also been suggested by Schawinski et al (2015).…”

The effect of accretion environment at large radius on hot accretion flows

“…There are also authors focus on AGNs feedback effects on kilo parsec scale (e.g. Di Ciotti, Ostriker & Proga 2009;Gan et al 2014;Ciotti et al 2017). The study of feedback effects at parsec scale is more direct to study interaction between the activities of AGNs and the accretion environment, because in these studies the inner boundary of computational domain can be placed at the location close to the boundary of accretion disk.…”

“…Then a question is that what kind of environment can harbour a LLAGN. 2) Gan et al (2014) studied the effect of strong radiative feedback from the LLAGNs, but they focus on the region of 2.5 pc − 250 kpc. Yuan et al (2009) pointed out that in the parsec and sub-parsec region, the global Compton scattering effect is already important.…”

On the wind production from hot accretion flows with different accretion rates

“…In the cosmological simulations studying galaxy formation and evolution (e.g., Springel et al 2005;Gan et al 2014), the Bondi radius can at most be marginally resolved. The authors use sub-grid models to study the black hole growth and AGNs feedback.…”