Delvecchio, I, Daddi, E, Aird, J et al. (10 more authors) (2020) The Evolving AGN Duty Cycle in Galaxies Since z ∼ 3 as Encoded in the X-Ray Luminosity Function. The Astrophysical Journal, 892 (1). 17. ISSN 0004-637X
Abstract
We present a new modeling of the X-ray luminosity function (XLF) of active galactic nuclei (AGNs) out to z ~ 3, dissecting the contributions of main-sequence (MS) and starburst (SB) galaxies. For each galaxy population, we convolved the observed galaxy stellar mass (Msstarf) function with a grid of Msstarf-independent Eddington ratio (λEDD) distributions, normalized via empirical black hole accretion rate (BHAR) to star formation rate (SFR) relations. Our simple approach yields an excellent agreement with the observed XLF since z ~ 3. We find that the redshift evolution of the observed XLF can only be reproduced through an intrinsic flattening of the λEDD distribution and with a positive shift of the break λ*, consistent with an antihierarchical behavior. The AGN accretion history is predominantly made by massive (1010 < Msstarf < 1011 M⊙) MS galaxies, while SB-driven BH accretion, possibly associated with galaxy mergers, becomes dominant only in bright quasars, at log(LX/erg s−1) > 44.36 + 1.28 × (1 + z). We infer that the probability of finding highly accreting (λEDD > 10%) AGNs significantly increases with redshift, from 0.4% (3.0%) at z = 0.5%–6.5% (15.3%) at z = 3 for MS (SB) galaxies, implying a longer AGN duty cycle in the early universe. Our results strongly favor a Msstarf-dependent ratio between BHAR and SFR, as BHAR/SFR ∝ ${M}_{\star }^{0.73[+0.22,-0.29]}$, supporting a nonlinear BH buildup relative to the host. Finally, this framework opens potential questions on super-Eddington BH accretion and different λEDD prescriptions for understanding the cosmic BH mass assembly.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2020. The American Astronomical Society. All rights reserved. This is an author-created, un-copyedited version of an article published in Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.3847/1538-4357/ab789c. |
Keywords: | AGN host galaxies ; Starburst galaxies ; Active galactic nuclei ; Active galaxies ; Galaxy evolution |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Pure Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 23 Sep 2020 09:17 |
Last Modified: | 23 Mar 2021 01:38 |
Published Version: | http://dx.doi.org/10.3847/1538-4357/ab789c |
Status: | Published |
Publisher: | American Astronomical Society |
Identification Number: | 10.3847/1538-4357/ab789c |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:165771 |