Feeding and Small-scale Feedback in Low-Luminosity AGNs

TL;DR

This paper models gas inflow and feedback mechanisms near supermassive black holes in low-luminosity AGNs, explaining observed density profiles and radiation through self-consistent simulations of accretion flows influenced by stellar winds and feedback.

Contribution

It introduces a self-consistent model of gas feeding and small-scale feedback in low-luminosity AGNs, incorporating stellar winds and conduction effects to match observations.

Findings

Density profiles are flatter due to conduction feedback.

Hot stellar winds primarily supply gas to the accretion region.

Models reproduce observed radio/sub-mm emissions near the event horizon.

Abstract

The unmatched X-ray resolution of Chandra allows probing the gas flow near quiescent supermassive black holes (BHs). The radius of BH gravitational influence on gas, called the Bondi radius, is resolved in Sgr A* and NGC 3115. Shallow accretion flow density profiles n \sim r^{-beta} with beta=0.7-1.0 were found for Sgr A* and NGC 3115 with the help of Chandra. We construct self-consistent models with gas feeding and dynamics from near the Bondi radius to the event horizon to explain the observations. Gas is mainly supplied to the region by hot colliding stellar winds. Small-scale feedback such as conduction effectively flattens the density profile from steep beta=1.5 in a Bondi flow. We further constrain density and temperature profiles using the observed radio/sub-mm radiation emitted near the event horizon. We discuss the present state of our numerical model and its qualitative features, such as the role of the galactic gravitational potential and the random motion of wind-emitting stars.