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Grand unification of AGN activity in the ΛCDM cosmology

Fanidakis, N. and Baugh, C. M. and Benson, A. J. and Bower, R. G. and Cole, S. and Done, C. and Frenk, C. S. (2011) Grand unification of AGN activity in the ΛCDM cosmology. Monthly Notices of the Royal Astronomical Society, 410 (1). pp. 53-74. ISSN 0035-8711. doi:10.1111/j.1365-2966.2010.17427.x.

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We track the coevolution of supermassive black holes (SMBHs) and their host galaxies through cosmic time. The calculation is embedded in the GALFORM semi-analytic model which simulates the formation and evolution of galaxies in a cold dark matter (CDM) universe. The black hole (BH) and galaxy formation models are coupled: during the evolution of the host galaxy, hot and cold gas are added to the SMBH by flows triggered by halo gas cooling, disc instabilities and galaxy mergers. This builds up the mass and spin of the BH, and the resulting accretion power regulates gas cooling and subsequent star formation. The accretion flow is assumed to form a geometrically thin cool disc when the accretion rate exceeds Graphic, and a geometrically thick, radiatively inefficient hot flow when the accretion rate falls below this value. The resulting quasar optical luminosity function matches observations well, and the mass of the SMBH correlates with the mass of the galaxy bulge as in the observed Mbh–Mbulge relation. The BH spin distribution depends strongly on whether we assume that the gas in any given accretion episode remains in the same plane or it fragments into multiple, randomly aligned accretion episodes due to its self-gravity. We refer to these cases as the ‘prolonged’ and ‘chaotic’ accretion modes, respectively. In the chaotic accretion model there is a clear correlation of spin with SMBH mass (and hence host galaxy bulge mass). Massive BHs (M > 5 × 108 M⊙) are hosted by giant elliptical galaxies and are rapidly spinning, while lower mass BHs are hosted in spiral galaxies and have much lower spin. Using the Blandford–Znajek mechanism for jet production to calculate the jet power, our model reproduces the radio loudness of radio galaxies, low ionization emission regions (LINERS) and Seyferts, suggesting that the jet properties of active galaxy nuclei (AGN) are a natural consequence of both the accretion rate on to and the spin of the central SMBH. This is the first confirmation that a CDM galaxy formation model can reproduce the observed radio phenomenology of AGN.

Item Type:Article
Related URLs:
URLURL TypeDescription
Baugh, C. M.0000-0002-9935-9755
Benson, A. J.0000-0001-5501-6008
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 July 26. Received 2010 July 18; in original form 2010 January 13. Article first published online: 8 Oct. 2010. We thank an anonymous referee for useful suggestions that have improved our paper. NF acknowledges receipt of a fellowship funded by the European Commission's Framework Programme 6, through the Marie Curie Early Stage Training project MEST-CT-2005-021074. AJB acknowledges the support of the Gordon & Betty Moore Foundation. CSF acknowledges a Royal Society Wolfson Research Merit Award. This work was supported in part by an STFC Rolling Grant to the Institute for Computational Cosmology.
Funding AgencyGrant Number
Marie Curie FellowshipMEST-CT-2005-021074
Gordon and Betty Moore FoundationUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords:methods: numerical – galaxies: active – galaxies: jets – galaxies: nuclei – quasars: general
Issue or Number:1
Record Number:CaltechAUTHORS:20110124-144934530
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Official Citation:Fanidakis, N., Baugh, C. M., Benson, A. J., Bower, R. G., Cole, S., Done, C. and Frenk, C. S. (2011), Grand unification of AGN activity in the ΛCDM cosmology. Monthly Notices of the Royal Astronomical Society, 410: 53–74. doi: 10.1111/j.1365-2966.2010.17427.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21868
Deposited By: Benjamin Perez
Deposited On:24 Jan 2011 23:29
Last Modified:09 Nov 2021 16:01

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