Do circumnuclear dense gas disks drive mass accretion onto supermassive black holes?

We present a positive correlation between the mass of dense molecular gas ($M_{dense}$) of ∼100 pc scale circumnuclear disks (CNDs) and the black hole mass accretion rate (${\dot{M}}_{BH}$) in a total of 10 Seyfert galaxies, based on data compiled from the literature and an archive (median aperture θ _med = 220 pc). A typical $M_{dense}$ of CNDs is 10^7–8 $M_{\odot }$, estimated from the luminosity of the dense gas tracer, the HCN(1–0) emission line. Because dense molecular gas is the site of star formation, this correlation is virtually equivalent to the one between the nuclear star-formation rate and ${\dot{M}}_{BH}$ revealed previously. Moreover, the $M_{dense}\text{--}{\dot{M}}_{BH}$ correlation was tighter for CND-scale gas than for the gas on kiloparsec or larger scales. This indicates that CNDs likely play an important role in fueling black holes, whereas greater than kiloparesec scale gas does not. To demonstrate a possible approach for studying the CND-scale accretion process with the Atacama Large Millimeter/submillimeter Array, we used a mass accretion model where angular momentum loss due to supernova explosions is vital. Based on the model prediction, we suggest that only the partial fraction of the mass accreted from the CND (${\dot{M}}_{acc}$) is consumed as ${\dot{M}}_{BH}$. However, ${\dot{M}}_{acc}$ agrees well with the total nuclear mass flow rate (i.e., ${\dot{M}}_{BH}$ + outflow rate). Although these results are still tentative with large uncertainties, they support the view that star formation in CNDs can drive mass accretion onto supermassive black holes in Seyfert galaxies.