Black Hole and Galaxy Coevolution in Moderately Luminous Active Galactic Nuclei at z ∼ 1.4 in SXDF

Abstract

We investigate the relation of black hole mass versus host stellar mass and that of mass accretion rate versus star formation rate (SFR) in moderately luminous ( ), X-ray selected broad-line active galactic nuclei (AGNs) at z = 1.18–1.68 in the Subaru/XMM-Newton Deep Field. The far-infrared to far-ultraviolet spectral energy distributions of 85 AGNs are reproduced with the latest version of Code Investigating GALaxy Emission ( CIGALE ), where the AGN clumpy torus model SKIRTOR is implemented. Most of their hosts are confirmed to be main-sequence star-forming galaxies. We find that the mean ratio of the black hole mass ( M BH ) to the total stellar mass ( M stellar ) is , which is similar to the local black hole–to–bulge mass ratio. This suggests that if the host galaxies of these moderately luminous AGNs at z ∼ 1.4 are dominated by bulges, they already established the local black hole mass–bulge mass relation; if they are disk dominant, their black holes are overmassive relative to the bulges. The AGN bolometric luminosities and SFR show a good correlation with ratios higher than that expected from the local black hole-to-bulge mass relation, suggesting that these AGNs are in a SMBH-growth dominant phase.