Institute of Astronomy

The role of AGN feedback in dwarf galaxies

SpeakerTalk DateTalk Series
Sophie Koudmani (IoA)24 November 2021Institute of Astronomy Seminars


Contrary to the standard lore, there is mounting observational evidence that feedback from active galactic nuclei (AGN) may also play a role at the low-mass end of the galaxy population. In this talk, I will explore that possibility, employing both cosmological boxes and high-resolution cosmological zoom-in simulations of dwarf galaxies.

Firstly, I will focus on the dwarf AGN population in the cosmological simulation suite FABLE. While in the local Universe the majority of AGN in dwarfs are much dimmer than the stellar component, for z ≥ 2 there is a significant AGN population that outshine their hosts and contribute to the suppression of star formation. Our results are overall in good agreement with X-ray observations of AGN in dwarfs, and we predict that future observations (including JWST, RST, Athena and Lynx) may uncover many more AGN in dwarfs with lower luminosities and at higher redshifts.

To examine AGN activity in dwarfs in more detail, we have performed a series of high-resolution zoom-in simulations, varying the AGN prescription and supernova (SN) energetics. We find that there are sufficient amounts of gas to power brief, Eddington-limited accretion episodes in dwarf galaxies. These episodes have a profound effect on the large-scale outflows, increasing outflow temperatures and velocities, which could be probed by future observations with JWST NIRSpec. The AGN-boosted outflows heat the circumgalactic medium and regulate star formation via maintenance-mode feedback, with the most significant impact at high redshifts, where SN feedback alone cannot suppress cosmic inflows efficiently.


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