Simulating galaxy formation with black hole driven thermal and kinetic feedback

Abstract

The inefficiency of star formation in massive elliptical galaxies is widely believed to be caused by the interactions of an active galactic nucleus (AGN) with the surrounding gas. Achieving a sufficiently rapid reddening of moderately massive galaxies without expelling too many baryons has however proven difficult for hydrodynamical simulations of galaxy formation, prompting us to explore a new model for the accretion and feedback effects of supermassive black holes. For high accretion rates relative to the Eddington limit, we assume that a fraction of the accreted rest mass energy heats the surrounding gas thermally, similar to the 'quasar mode' in previous work. For low accretion rates, we invoke a new, pure kinetic feedback model that imparts momentum to the surrounding gas in a stochastic manner. These two modes of feedback are motivated both by theoretical conjectures for the existence of different types of accretion flows as well as recent observational evidence for the importance of kinetic AGN winds in quenching galaxies. We find that a large fraction of the injected kinetic energy in this mode thermalizes via shocks in the surrounding gas, thereby providing a distributed heating channel. In cosmological simulations, the resulting model produces red, non star-forming massive elliptical galaxies, and achieves realistic gas fractions, black hole growth histories and thermodynamic profiles in large haloes.

The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation

“…The simulation is evolved using the AREPO code (Springel 2010) and follows self-gravity, magnetohydrodynamics, radiative cooling, star-formation, and an updated set of sub-grid physics models for stellar evolution, black hole growth, and stellar and AGN feedback (Weinberger et al 2017a;Pillepich et al 2017b). We developed the fiducial physical model used to evolve TNG100 with the help of a series of tuning tests on smaller cosmological boxes, with the goal of roughly reproducing several galaxy scaling relations.…”

Increasing Black Hole Feedback-induced Quenching with Anisotropic Thermal Conduction

“…The simulations employ a galaxy formation physics model originally developed for the ILLUSTRIS simulation suite (Vogelsberger et al 2012(Vogelsberger et al , 2014a(Vogelsberger et al , 2014b, updated with a new AGN feedback scheme (Weinberger et al 2017) and modifications to the stellar wind scheme (A. Pillepich et al 2017, in preparation).…”

“…Feedback from active galactic nuclei (AGNs) has widely been invoked to explain the quenching and quiescence of massive galaxies (Croton et al 2006;Sijacki et al 2007;Booth & Schaye 2009;Gaspari et al 2011;Choi et al 2012;Li & Bryan 2014;Weinberger et al 2017). However, the details of how this feedback energy couples to the surrounding gas are still not properly understood, so the modeling efforts have been necessarily crude.…”

“…However, the details of how this feedback energy couples to the surrounding gas are still not properly understood, so the modeling efforts have been necessarily crude. Despite this limitation, recent cosmological models have had reasonable success in regulating the properties of massive central galaxies (e.g., Genel et al 2014;Vogelsberger et al 2014a;Schaye et al 2015;Sijacki et al 2015;Weinberger et al 2017).…”

The jet feedback mechanism (JFM) in stars, galaxies and clusters

“…There is a large body of literature on feedback processes during the epoch of galaxy formation, including feedback from stars, mainly through supernovae, and from AGN, by radiation and/or jets/outflows (e.g., Cattaneo et al 2009;Alexander & Hickox 2012;Fabian 2012;Kormendy & Ho 2013;Heckman & Best 2014;King & Pounds 2015; Tadhunter 2016 for reviews, and, e.g., Wagner et al 2016;Bongiorno et al 2016;Weinberger et al 2016 for recent papers on the AGN-JFM). In this section I review only the AGN-JFM, and concentrate only on processes that are related to other objects that are reviewed here, in particular to cooling flows in clusters of galaxies.…”