ALBERT

Description: Recent studies show that a universal relation between black-hole (BH) growth and stellar mass (M⋆) or star formation rate (SFR) is an oversimplification of BH-galaxy co-evolution, and that morphological and structural properties of host galaxies must also be considered. Particularly, a possible connection between BH growth and host-galaxy compactness was identified among star-forming (SF) galaxies. Utilizing ≈6300 massive galaxies with I814W  〈  24 at z 〈 1.2 in the COSMOS field, we perform systematic partial-correlation analyses to investigate how sample-averaged BH accretion rate ($ m overline{BHAR}$) depends on host-galaxy compactness among SF galaxies, when controlling for morphology and M⋆ (or SFR). The projected central surface-mass density within 1 kpc, Σ1, is utilized to represent host-galaxy compactness in our study. We find that the $ m overline{BHAR}$-Σ1 relation is stronger than either the $ m overline{BHAR}$-M⋆ or $ m overline{BHAR}$-SFR relation among SF galaxies, and this $ m overline{BHAR}$-Σ1 relation applies to both bulge-dominated galaxies and galaxies that are not dominated by bulges. This $ m overline{BHAR}$-Σ1 relation among SF galaxies suggests a link between BH growth and the central gas density of host galaxies on the kpc scale, which may further imply a common origin of the gas in the vicinity of the BH and in the central ∼ kpc of the galaxy. This $ m overline{BHAR}$-Σ1 relation can also be interpreted as the relation between BH growth and the central velocity dispersion of host galaxies at a given gas content (i.e. gas mass fraction), indicating the role of the host-galaxy potential well in regulating accretion onto the BH.