Influence of AGN Outbursts on the Surrounding Galaxies

TL;DR

This study models how powerful AGN outbursts can strip gas from surrounding galaxies, reducing star formation, especially at high redshift, highlighting a feedback mechanism in galaxy evolution.

Contribution

It introduces a calculation of shock impacts from AGN outbursts on group galaxies, emphasizing effects at high redshift and the potential for feedback.

Findings

Extreme AGN outbursts can strip cold gas from galaxy discs.

Outer halo gas can be stripped even at lower energies.

This mechanism is more relevant at high redshift.

Abstract

We study the influence of a strong AGN outburst on the surrounding galaxies. The AGN is assumed to reside in a group of galaxies, and an outburst excites a shock wave in the hot gas in the group. We calculate the impact of the shock wave on the galaxies. We find that if the energy of the outburst is extremely large (E_AGN ~6x10^61 erg) as the one recently observed in clusters, the impact is strong enough to strip the cold interstellar medium in the disc of the galaxies in the inner region of the group. Moreover, even in the outer region of the group, the warm gas in the halo of the galaxies would be stripped, even if the energy of the outburst is ~6x10^60 erg. These would decrease star formation activity of the galaxies. If these galaxies fall into the group centre through dynamical friction and their interstellar medium is the fuel of the supermassive black hole in the AGN, the outburst would serve as feedback. While this mechanism works only when E_AGN is extremely large, such outbursts have not been observed in groups at low redshift; it would work at high redshift rather than at low redshift.