Evident black hole-bulge coevolution in the distant universe. Issue 3 (2nd March 2019)

• Record Type: Journal Article
• Authors: Yang(杨光), G; Brandt, W N; Alexander, D M; Chen(陳建廷), C-T J; Ni(倪清泠), Q; Vito, F; Zhu(朱飞凡), F-F
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 485:Issue 3(2019)
• Page Start: 3721
• Page End: 3737
• Publication Date: 2019-03-02
• Subjects: galaxies: active -- galaxies: bulges -- galaxies: evolution -- galaxies: nuclei -- X-rays: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz611
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Observations in the local universe show a tight correlation between the masses of supermassive black holes (SMBHs; M BH ) and host-galaxy bulges ( M bulge ), 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 ($\overline{\rm BHAR}$ ) for bulge-dominated galaxies at z = 0.5–3. While previous observations found$\overline{\rm BHAR}$ is strongly related to host-galaxy stellar mass ( M ⋆ ) for the overall galaxy population, our analyses show that, for the bulge-dominated population, $\overline{\rm BHAR}$ is mainly related to SFR rather than M ⋆ . This${\overline{\rm BHAR}}$ –SFR relation is highly significant, e.g. 9.0σ (Pearson statistic) at z = 0.5–1.5. Such a$\overline{\rm BHAR}$ –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 M BH − M bulge correlation. Our best-fitting${\overline{\rm BHAR}}$ –SFR relation for the bulge-dominated sample is${\log \overline{\rm BHAR}= \log \mathrm{SFR} - (2.48\pm 0.05)}$ (solar units). The best-fitting$\overline{\rm BHAR}/\mathrm{SFR}$ ratio (10 −2.48 ) for bulge-dominated galaxies is similar to the observed M BH / M bulge 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 M BH − M bulge correlation. This lockstep growth also predicts that the M BH − M bulge relation should not have strong redshift dependence.