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

Abstract

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.

Citation

Yang(杨光), G., Brandt, W., Alexander, D., Chen(陳建廷), C., Ni(倪清泠), Q., Vito, F., & Zhu(朱飞凡), F. (2019). Evident black hole-bulge coevolution in the distant universe. Monthly Notices of the Royal Astronomical Society, 485(3), 3721-3737. https://doi.org/10.1093/mnras/stz611

• 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
• DOI: https://doi.org/10.1093/mnras/stz611
• Related Public URLs: https://arxiv.org/abs/1903.00003