Black Hole Feedback in New Regimes: Modelling Dwarf Galaxies with Active Galactic Nuclei

Speaker: 
Sophie Koudmani (University of Cambridge)
Date: 
Friday, March 26, 2021 - 10:00am to 11:00am

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 impact of AGN feedback on dwarfs in the cosmological simulation suite FABLE. At high redshifts (z ≥ 2) AGN feedback contributes to the quenching of dwarfs, whereas at late cosmic times supernova (SN) feedback is more efficient. Dwarfs with efficient black hole growth drive more powerful outflows, reaching higher outflow velocities and temperatures, throughout cosmic time. Furthermore, the enhanced outflows lead to kinematic offsets in mock IFU maps, in agreement with recent MaNGA observations.
 
The AGN luminosity distributions of FABLE’s dwarfs are overall consistent with local observations, and FABLE predicts that future observations (including JWST, RST, Athena and Lynx) may uncover many more AGN in dwarfs with lower luminosities and at higher redshifts. However, the lack of high-luminosity X-ray AGN in FABLE at low redshifts highlights an interesting possibility that SN feedback could be too strong in FABLE's dwarfs, curtailing AGN growth and feedback.
 
To examine the interplay between SNe and AGN accretion in more detail, I have performed a series of zoom-in simulations, varying the AGN prescription and SN energetics. I 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 and inflows as well as the star formation rates, which could be probed by future observations with JWST NIRSpec and ALMA.

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