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Evident black hole-bulge coevolution in the distant universe

Yang(杨光), G; Brandt, WN; Alexander, DM; Chen(陳建廷), C-TJ; Ni(倪清泠), Q; Vito, F; Zhu(朱飞凡), F-F

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G Yang(杨光)

WN Brandt

C-TJ Chen(陳建廷)

Q Ni(倪清泠)

F Vito

F-F Zhu(朱飞凡)


Observations in the local universe show a tight correlation between the masses of supermassive black holes (SMBHs; MBH) and host-galaxy bulges (Mbulge), suggesting a strong connection between SMBH and bulge growth.However, direct evidence for such a connection in the distant universe remains elusive. We have studied sample-averaged SMBH accretion rate (BHAR) for bulge-dominated galaxies at z = 0.5–3. While previous observations found BHAR is strongly related to host-galaxy stellar mass (M) for the overall galaxy population, our analyses show that, for the bulge-dominated population, BHAR is mainly related to SFR rather than M. This BHAR–SFR relation is highly significant, e.g. 9.0σ (Pearson statistic) at z = 0.5–1.5. Such a BHAR–SFR connection does not exist among our comparison sample of galaxies that are not bulge dominated, for which M appears to be the main determinant of SMBH accretion. This difference between the bulge-dominated and comparison samples indicates that SMBHs only coevolve with bulges rather than the entire galaxies, explaining the tightness of the local MBH−Mbulge correlation. Our best-fitting BHAR–SFR relation for the bulge-dominated sample is logBHAR = log SFR − (2.48 ± 0.05) (solar units). The best-fitting BHAR/SFR ratio (10−2.48) for bulge-dominated galaxies is similar to the observed MBH/Mbulge values in the local universe. Our results reveal that SMBH and bulge growth are in lockstep, and thus non-causal scenarios of merger averaging are unlikely the origin of the MBH−Mbulge correlation. This lockstep growth also predicts that the MBH−Mbulge relation should not have strong redshift dependence.

Journal Article Type Article
Acceptance Date Feb 26, 2019
Online Publication Date Mar 2, 2019
Publication Date May 31, 2019
Deposit Date Jul 30, 2019
Publicly Available Date Jul 31, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 485
Issue 3
Pages 3721-3737
Public URL
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Published Journal Article (2.5 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Author[s]. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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