Evident black hole-bulge coevolution in the distant universe

Abstract

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 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 (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 M BH −M bulge correlation. Our best-fitting BHAR-SFR relation for the bulge-dominated sample is log BHAR = 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 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.

Does black hole growth depend fundamentally on host-galaxy compactness?

“…The redshift, stellar mass (M ), and star formation rate (SFR) used in this paper are identical to those used in Yang et al (2019). We obtain redshift measurements from the CANDELS catalogs (see Table 1).…”

“…Could the observed high AGN fraction among compact star-forming galaxies in Kocevski et al (2017) be a natural consequence of a large amount of BH growth expected among star-forming bulges (e.g. Silverman et al 2008;Yang et al 2019)? Or, if compactness is indeed a critical property linked with BH growth, perhaps serving as an indicator of central gas density, could the relation between BH growth and M found in Yang et al (2017Yang et al ( , 2018a) simply be reflecting this linkage?…”

“…Or, if compactness is indeed a critical property linked with BH growth, perhaps serving as an indicator of central gas density, could the relation between BH growth and M found in Yang et al (2017Yang et al ( , 2018a) simply be reflecting this linkage? Could the relation between BH growth and SFR among bulge-dominated galaxies presented in Yang et al (2019) simply be a manifestation of the predicted compact starburst with concurrent BH growth?…”

x-cigale: fitting AGN/galaxy SEDs from X-ray to infrared

“…This quantity, paired with an assumed radiative efficiency, can be used to estimate BH accretion rate (e.g. Yang et al 2017Yang et al , 2019. This paper has been typeset from a T E X/L A T E X file prepared by the author.…”

“…Therefore, X-ray fluxes are widely used as a tracer of BH accretion rate (e.g. Yang et al 2018aYang et al , 2019. Thanks to their great penetrating power, X-rays are only mildly affected by obscuration in general.…”