Do stellar winds play a decisive role in feeding AGN?

TL;DR

This paper explores how stellar winds influence gas inflow towards active galactic nuclei (AGN), suggesting that feedback from star formation on small scales can both hinder and facilitate accretion, impacting the structure of the obscuring torus.

Contribution

It introduces the role of stellar feedback at tens of parsecs in regulating gas inflow and the formation of the AGN torus, highlighting a dynamic link between star formation and AGN feeding.

Findings

Stellar feedback initially hinders gas accretion by inducing turbulence.

After turbulence subsides, stellar winds enable efficient gas inflow.

The properties of the obscuring torus are linked to star formation activity.

Abstract

While the existence of a starburst-AGN connection is undisputed, there is no consensus on what the connection is. In this contribution, we begin by noting that the mechanisms which drive gas inwards in disk galaxies are generally inefficient at removing angular momentum, leading to stalled inflows. Thus, a tiered series of such processes is required to bring gas to the smallest scales, each of which on its own may not correlate with the presence of an AGN. Similarly, each may be associated with a starburst event, making it important to discriminate between 'circumnuclear' and 'nuclear' star formation. In this contribution, we show that stellar feedback on scales of tens of parsecs plays a critical role in first hindering and then helping accretion. We argue that it is only after the initial turbulent phases of a starburst that gas from slow stellar winds can accrete efficiently to smaller scales. This would imply that the properties of the obscuring torus are directly coupled to star formation and that the torus must be a complex dynamical entity. We finish by remarking on other contexts where similar processes appear to be at work.