It is feeding that makes black holes ‘visible’: almost everything we know about them is derived from the properties of accreting massive black holes – AGN and quasars.

Gas permeates galaxies, it is used up to form stars, but it is also replenished though accretion from the cosmic web, and through mergers with other galaxies. How gas trickles all the way down to the black hole capture region is one of the outstanding problems since the discovery of quasars.

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Projected gas density on different scales of the main galaxy in the  cosmological hydrodynamical simulation “Seth”, at z=3.25. We can admire the complex patterns of gas flows, from the cosmic web all the way to the nucleus. From Dubois et al. 2015, MNRAS, 452, 1502.

The energy released by an accreting black hole, feedback, also impacts the very gas feeding it. To study how gas flows in and out of the black hole region one has to resolve the nuclear scales where massive black holes dominate.

We use analytical, semi-analytical methods,  as well as numerical simulations to study how gas feeds black holes, while at the same time star formation and feedback affect the gas dynamics and thermodynamics.