The impact of AGN wind feedback in simulations of isolated galaxies with a multiphase ISM

Paul Torrey,Eliot Quataert,Xiangcheng Ma,Dusan Keres,Claude-André Faucher-Giguère,Daniel Anglés-Alcázar,Norm Murray,Robert Feldmann,Philip F Hopkins

doi:10.1093/mnras/staa2222

Abstract

ABSTRACT Accreting black holes can drive fast and energetic nuclear winds that may be an important feedback mechanism associated with active galactic nuclei (AGN). In this paper, we implement a scheme for capturing feedback from these fast nuclear winds and examine their impact in simulations of isolated disc galaxies. Stellar feedback is modelled using the Feedback In Realistic Environments (fire) physics and produces a realistic multiphase interstellar medium (ISM). We find that AGN winds drive the formation of a low-density, high-temperature central gas cavity that is broadly consistent with analytic model expectations. The effects of AGN feedback on the host galaxy are a strong function of the wind kinetic power and momentum. Low- and moderate-luminosity AGN do not have a significant effect on their host galaxy: the AGN winds inefficiently couple to the ambient ISM and instead a significant fraction of their energy vents in the polar direction. For such massive black holes, accretion near the Eddington limit can have a dramatic impact on the host galaxy ISM: if AGN wind feedback acts for ≳20–30 Myr, the inner ∼1–10 kpc of the ISM is disrupted and the global galaxy star formation rate is significantly reduced. We quantify the properties of the resulting galaxy-scale outflows and find that the radial momentum in the outflow is boosted by a factor of ∼2–3 relative to that initially supplied in the AGN wind for strong feedback scenarios, decreasing below unity for less energetic winds. In contrast to observations, however, the outflows are primarily hot, with very little atomic or molecular gas. We conjecture that merging galaxies and high-redshift galaxies, which have more turbulent and thicker discs and very different nuclear gas geometries, may be even more disrupted by AGN winds than found in our simulations.

Highlights

Feedback from supermassive black holes – commonly called active galactic nuclei (AGN) feedback – has been postulated as an important component of galaxy formation
While it is broadly accepted that supermassive black holes are present at the centre of all massive galaxies (e.g. Ho 2008) and that they can release sufficiently large amounts of energy during accretion events to remove all gas from a galaxy (e.g. Ciotti & Ostriker 1997; Silk & Rees 1998; King 2003; Wyithe & Loeb 2003; Murray, Quataert & Thompson 2005), the actual significance of AGN feedback on the formation history of their host galaxy remains an unsettled and debated topic
We used numerical simulations to study the evolution of an energetic, kinetic wind that is launched from a central, accreting supermassive black hole

Summary

Introduction

Feedback from supermassive black holes – commonly called active galactic nuclei (AGN) feedback – has been postulated as an important component of galaxy formation. Perhaps the best empirical motivation that galaxies regulate their growth through AGN feedback is the existence of tight correlations between supermassive black hole mass and host galaxy properties – such as bulge mass and velocity dispersion (Ferrarese & Merritt 2000; Gebhardt et al 2000). These black hole/host galaxy scaling relations can be explained if black hole feedback regulates its own growth and perhaps the stellar mass growth of the host galaxy. In addition to the scaling relations, observations of bright quasars show outflowing

Methods

Discussion

Conclusion