2020ApJ...889...84K

We study the obscuring structure of circumnuclear disks (CNDs) by considering supernova (SN) feedbacks from nuclear starburst and the effect of anisotropic radiative pressure from active galactic nuclei (AGNs). We suppose that the mass accretion onto a central supermassive black hole (SMBH) is triggered by SN-driven turbulence within CNDs, and we explore how the structures of CNDs depend on the BH mass (M_BH) and AGN luminosity (L_AGN). We find that the obscuring fraction (f_obs) peaks at ∼10% of the Eddington luminosity (L_Edd), and its maximal value is f_obs ∼ 0.6 for less massive SMBHs (e.g., M_BH < 10⁸ M_☉). This is because the scale height of CNDs is determined by the SN-driven accretion for a smaller L_AGN, while the dusty molecular gas in CNDs is blown away by the radiation pressure from AGNs beyond the critical luminosity. On the other hand, for massive SMBHs (e.g., M_BH > 10⁸ M_☉), f_obs is always smaller than 0.2, and it is almost independent of L_AGN because the scale height of CNDs is mainly controlled by the maximal star formation efficiency (C_* ,{max}_) in CNDs. In comparison with the obscuring fractions suggested from the mid-infrared observations of nearby AGNs, the SN plus radiative feedback model with C_* ,{max}_=10^–7yr^–1 reproduces the observations for M_BH = 10⁸ M_☉ well. We also find that the intense starburst or the existence of dust-free absorbers inside CNDs are necessary for explaining X-ray observations.