Bernhard, E., Mullaney, J.R., Aird, J. et al. (5 more authors) (2018) Evidence for a mass-dependent AGN Eddington ratio distribution via the flat relationship between SFR and AGN luminosity. Monthly Notices of the Royal Astronomical Society, 476 (1). pp. 436-450. ISSN 0035-8711
Abstract
The lack of a strong correlation between AGN X-ray luminosity (L X ; a proxy for AGN power) and the star formation rate (SFR) of their host galaxies has recently been attributed to stochastic AGNvariability. Studies using population synthesis models have incorporated this by assuming a broad, universal (i.e. does not depend on the host galaxy properties) probability distribution for AGN specific X-ray luminosities (i.e. the ratio of L X to host stellar mass; a common proxy for Eddington ratio). However, recent studies have demonstrated that this universal Eddington ratio distribution fails to reproduce the observed X-ray luminosity functions beyond z ~ 1.2. Furthermore, empirical studies have recently shown that the Eddington ratio distribution may instead depend upon host galaxy properties, such as SFR and/or stellarmass. To investigate this further, we develop a population synthesis model in which the Eddington ratio distribution is different for star-forming and quiescent host galaxies. We showthat, although this model is able to reproduce the observed X-ray luminosity functions out to z ~ 2, it fails to simultaneously reproduce the observed flat relationship between SFR and X-ray luminosity. We can solve this, however, by incorporating a mass dependency in the AGN Eddington ratio distribution for starforming host galaxies. Overall, our models indicate that a relative suppression of low Eddington ratios (λ Edd < ~0.1) in lower mass galaxies (M * < ~10 10-11 M⊙) is required to reproduce both the observed X-ray luminosity functions and the observed flat SFR/X-ray relationship.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | galaxies: active; galaxies: evolution ; galaxies: luminosity function ; mass function – galaxies: statistics |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Mar 2018 15:29 |
Last Modified: | 22 Mar 2018 15:30 |
Published Version: | https://doi.org/10.1093/mnras/sty219 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/sty219 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:128806 |