How Does Radio AGN Feedback Feed Back?

TL;DR

This paper models how radio AGN feedback heats surrounding gas through turbulence, potentially suppressing star formation, with a timescale comparable to gas cooling times in galaxies.

Contribution

It presents a detailed 3D MHD turbulence model for radio AGN feedback, linking outflow turbulence to heating timescales based on observations.

Findings

Heating onset time is about 100 million years.

Turbulent energy converts to heat within galaxy environments.

Heating locations align with observed FR-I outflows.

Abstract

Radio AGN feedback is often assumed to work, but detailed physical models of this process are not well developed. This paper examines a possible path for radio AGN feedback to heat the gas in and around galaxies and perhaps suppress star formation. Nearby radio AGN are almost all FR-I radio galaxies, and it is argued that such outflows become decelerated and fully turbulent in their early stages. A 3D non-linear MHD turbulence calculation is made to determine the time required for this outflowing turbulent energy to be converted into heat. Using radio and x-ray observations of nearby FR-I AGN for normalization results in a time for the onset of heating of about 100 million years. This is comparable to the gas cooling times in and around galaxies, and the resulting location of heat deposition is consistent with FR-I outflows.