A little FABLE: exploring AGN feedback in dwarf galaxies with cosmological simulations

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. We investigate this using the cosmological
simulation suite FABLE, with a particular focus on the dwarf regime
($M_mathrm{stellar} < 10^{9.5} mathrm{M_{odot}}$). We find that
overmassive black holes (BHs), with respect to the mean scaling relations with
their host galaxies, drive hotter and faster outflows and lead to significantly
reduced gas mass fractions. They are also more likely to display a
kinematically misaligned ionized gas component in our mock MaNGA velocity maps,
although we caution that cosmic inflows and mergers contribute to misalignments
as well. While in the local Universe the majority of AGN in dwarfs are much
dimmer than the stellar component, for $z geq 2$ there is a significant
population that outshines their hosts. These high-redshift overmassive BHs
contribute to the quenching of dwarfs, whereas at late cosmic times supernova
(SN) feedback is more efficient. While our results are overall in good
agreement with X-ray observations of AGN in dwarfs, 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. We predict that future observations may uncover many more AGN in
dwarfs with lower luminosities and at higher redshifts.
Read More

Leave a Reply

Your email address will not be published. Required fields are marked *