Radio constraints on the volume filling factors of AGN winds

TL;DR

This paper uses radio emission observations to set upper limits on the volume filling factors of AGN winds, which are crucial for accurately estimating their mass outflow rates and understanding their impact on galaxy evolution.

Contribution

It introduces a method to constrain the volume filling factors of AGN winds using radio flux measurements, providing new upper limit estimates.

Findings

Upper limits to filling factors range from 10^{-4} to 0.5.

Radio emission can effectively constrain wind properties.

Method applied to nearby AGN samples.

Abstract

The calculation of mass outflow rates of AGN winds is of great importance in understanding the role that such winds play in AGN-galaxy feedback processes. The mass outflow rates are, however, difficult to estimate since the volume filling factors of the winds are unknown. In this paper, we use constraints imposed by the observed radio emission to obtain upper limits to the volume filling factors of wind components in certain nearby AGN. We do this by predicting the 1.4 GHz radio flux densities emitted by those components, assuming a uniform wind, and then comparing these with the observed flux densities for each AGN at this frequency. We find that the upper limits to the volume filling factors are in the range 10^{-4}-0.5.