Feedback from Active Galactic Nuclei in Galaxy Groups

TL;DR

This paper reviews how active galactic nuclei (AGN) influence galaxy groups through feedback mechanisms, affecting galaxy evolution and baryon distribution, with insights from observations, models, and future instrumentation.

Contribution

It provides a comprehensive overview of AGN feedback in galaxy groups, highlighting recent observational and theoretical advances and discussing implications for galaxy evolution models.

Findings

AGN feedback regulates cooling and heating in galaxy groups.

Energy from AGN can exceed the gravitational binding energy of halo gas.

Future instruments will address key open questions in the field.

Abstract

The co-evolution between supermassive black holes and their environment is most directly traced by the hot atmospheres of dark matter halos. Cooling of the hot atmosphere supplies the central regions with fresh gas, igniting active galactic nuclei (AGN) with long duty cycles. Outflows from the central engine tightly couple with the surrounding gaseous medium and provide the dominant heating source preventing runaway cooling by carving cavities and driving shocks across the medium. The AGN feedback loop is a key feature of all modern galaxy evolution models. Here we review our knowledge of the AGN feedback process in the specific context of galaxy groups. Galaxy groups are uniquely suited to constrain the mechanisms governing the cooling-heating balance. Unlike in more massive halos, the energy supplied by the central AGN to the hot intragroup medium can exceed the gravitational binding energy of halo gas particles. We report on the state-of-the-art in observations of the feedback phenomenon and in theoretical models of the heating-cooling balance in galaxy groups. We also describe how our knowledge of the AGN feedback process impacts on galaxy evolution models and on large-scale baryon distributions. Finally, we discuss how new instrumentation will answer key open questions on the topic.