2017ApJ...842...72Y

We investigate the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M_*) in the CANDELS/GOODS-South field in the redshift range of 0.5 z 2.0. Our sample consists of ~18,000 galaxies, allowing us to probe galaxies with 0.1M_☉yr^–1 SFR 100 M_☉ yr^–1 and/or 10⁸M_☉ M_* 10¹¹ M_☉. We use sample-mean BHAR to approximate long-term average BHAR. Our sample-mean BHARs are derived from the Chandra Deep Field-South 7 Ms observations, while the SFRs and M_* have been estimated by the CANDELS team through spectral energy distribution fitting. The average BHAR is correlated positively with both SFR and M_*, and the BHAR-SFR and BHAR-M_* relations can both be described acceptably by linear models with a slope of unity. However, BHAR appears to be correlated more strongly with M_* than SFR. This result indicates that M_* is the primary host-galaxy property related to supermassive black hole (SMBH) growth, and the apparent BHAR-SFR relation is largely a secondary effect due to the star-forming main sequence. Among our sources, massive galaxies (M_* 10¹⁰M_☉) have significantly higher BHAR/SFR ratios than less massive galaxies, indicating that the former have higher SMBH fueling efficiency and/or higher SMBH occupation fraction than the latter. Our results can naturally explain the observed proportionality between M_BH and M_* for local giant ellipticals and suggest that their M_BH/M_* is higher than that of local star-forming galaxies. Among local star-forming galaxies, massive systems might have higher M_BH/M_* compared to dwarfs.