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Published September 1, 2015 | Published + Submitted
Journal Article Open

The Illustris simulation: Evolving population of black holes across cosmic time


We study the properties of black holes and their host galaxies across cosmic time in the Illustris simulation. Illustris is a large-scale cosmological hydrodynamical simulation which resolves a (106.5 Mpc)^3 volume with more than 12 billion resolution elements and includes state-of-the-art physical models relevant for galaxy formation. We find that the black hole mass density for redshifts z = 0–5 and the black hole mass function at z = 0 predicted by Illustris are in very good agreement with the most recent observational constraints. We show that the bolometric and hard X-ray luminosity functions of active galactic nuclei (AGN) at z = 0 and 1 reproduce observational data very well over the full dynamic range probed. Unless the bolometric corrections are largely underestimated, this requires radiative efficiencies to be on average low, ϵ_r ≲ 0.1, noting however that in our model radiative efficiencies are degenerate with black hole feedback efficiencies. Cosmic downsizing of the AGN population is in broad agreement with the findings from X-ray surveys, but we predict a larger number density of faint AGN at high redshifts than currently inferred. We also study black hole–host galaxy scaling relations as a function of galaxy morphology, colour and specific star formation rate. We find that black holes and galaxies co-evolve at the massive end, but for low mass, blue and star-forming galaxies there is no tight relation with either their central black hole masses or the nuclear AGN activity.

Additional Information

© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 June 12. Received 2015 June 12. In original form 2014 August 28. First published online July 6, 2015. We would like to thank the referee for a very constructive referee report which improved this paper. DS would like to thank Martin Haehnelt, Manda Banerji, Roberto Maiolino, Matt Auger, Ranjan Vasudevan, Andy Fabian and Richard McMahon for very useful discussions. DS also would like to thank Manda Banerji for kindly providing the data compilation used in Fig. 13. Simulations were run on the Harvard Odyssey and CfA/ITC clusters, the Ranger and Stampede supercomputers at the Texas Advanced Computing Center as part of XSEDE, the Kraken supercomputer at Oak Ridge National Laboratory as part of XSEDE, the CURIE supercomputer at CEA/France as part of PRACE project RA0844 and the SuperMUC computer at the Leibniz Computing Centre, Germany, as part of project pr85je. VS acknowledges support by the DFG Research Centre SFB-881 'The Milky Way System' through project A1, and by the European Research Council under ERC-StG EXAGAL-308037. SG acknowledges support provided by NASA through Hubble Fellowship grant HST-HF2-51341.001-A awarded by the STScI, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. GFS acknowledges support from the HST grants program, numbers HST-AR-12856.01-A and HST-AR-13887.004A. Support for programs #12856 and #13887 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. LH acknowledges support from NASA grant NNX12AC67G and NSF grant AST-1312095.

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Submitted - 1408.6842v1.pdf

Published - MNRAS-2015-Sijacki-575-96.pdf


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August 22, 2023
August 22, 2023