2 research outputs found
Cosmological simulations of black hole growth: AGN luminosities and downsizing
In this study, we present a detailed, statistical analysis of black hole
growth and the evolution of active galactic nuclei (AGN) using cosmological
hydrodynamic simulations run down to . The simulations self-consistently
follow radiative cooling, star formation, metal enrichment, black hole growth
and associated feedback processes from both supernovae typeII/Ia and AGN. We
consider two simulation runs, one with a large co-moving volume of $(500\
\mathrm{Mpc})^3(68\ \mathrm{Mpc})^3z=3.0z=3-4$. We also perform
a direct comparison with the observed soft and hard X-ray luminosity functions
of AGN, including an empirical correction for a torus-level obscuration, and
find a similarly good agreement. These results nicely demonstrate that the
observed "anti-hierarchical" trend in the AGN number density evolution (i.e.
the number densities of luminous AGN peak at higher redshifts than those of
faint AGN) is self-consistently predicted by our simulations. Implications of
this downsizing behaviour on active black holes, their masses and
Eddington-ratios are discussed. Overall, the downsizing behaviour in the AGN
number density as a function of redshift can be mainly attributed to the
evolution of the gas density in the resolved vicinity of a (massive) black
hole. (shortened)Comment: 24 pages, 15 figures, 1 table, accepted for publication in MNRAS, the
analysis is updated using a simulation run with a cosmological volume of
(500Mpc)^3 containing 2*1,564^3 particle