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Register a new userTransition of BH feeding from the quiescent regime into star-forming cold disk regime
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We study the properties of rotating accretion flows onto supermassive black holes (SMBHs) using axisymmetric two-dimensional hydrodynamical simulations with radiative cooling and BH feedback. The simulations resolve the accretion dynamics of gas outside from the BH influence radius through an inner accretion disk. For lower Bondi accretion rates in units of the Eddington rate ($dot{M}_{rm B}ll 10^{-3}~dot{M}_{rm Edd}$), the BH feeding is suppressed due to turbulent motion by several orders of magnitudes from the Bondi rate. Thus, the radiative luminosity results in as low as $sim 10^{-10}-10^{-7}~L_{rm Edd}$, where $L_{rm Edd}$ is the Eddington luminosity. For higher rates of $dot{M}_{rm B}> 10^{-3}~dot{M}_{rm Edd}$, the optically-thin accreting gas cools via free-free emission and forms a geometrically-thin disk, which feeds the BH efficiently and increases the radiative luminosity to $> 10^{-3}~L_{rm Edd}$. The transitional behavior of accreting BHs in galactic nuclei from radiatively inefficient phases to cold disk accretion naturally explains (1) the reason for the offset between the observed luminosities and theoretical predictions for nearby quiescent SMBHs, and (2) the conditions to fuel gas into the nuclear SMBH. In addition, the cold disk formed in galactic nuclei tends to be gravitationally unstable and leads to star formation when the Bondi rate is as high as $ dot{M}_{rm B} > 10^{-2}~M_odot~{rm yr}^{-1}$. This is a plausible explanation of the correlation observed between star formation rates and BH feeding rates in Seyfert galaxies.
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The $M_{BH}$ - $sigma_{star}$ relation is considered a result of co-evolution between the host galaxies and their super-massive black holes. For elliptical-bulge hosting inactive galaxies, this relation is well established, but there is still a debate whether active galaxies follow the same relation. In this paper, we estimate black hole masses for a sample of 19 local luminous AGNs (LLAMA) in order to test their location on the $M_{BH}$ - $sigma_{star}$ relation. Super-massive black hole masses ($M_{BH}$) were derived from the broad-line based relations for H$alpha$, H$beta$ and Pa$beta$ emission line profiles for the Type 1 AGNs. We compare the bulge stellar velocity dispersion ($sigma_{star}$) as determined from the Ca II triplet (CaT) with the dispersion measured from the near-infrared CO (2-0) absorption features for each AGN and find them to be consistent with each other. We apply an extinction correction to the observed broad line fluxes and we correct the stellar velocity dispersion by an average rotation contribution as determined from spatially resolved stellar kinematic maps. The H$alpha$-based black hole masses of our sample of AGNs were estimated in the range 6.34 $leq$ $log{M_{BH}}$ $leq$ 7.75 M$_odot$ and the $sigma_{star CaT}$ estimates range between 73 $leq$ $sigma_{star CaT}$ $leq$ 227 km s$^{-1}$. From the so-constructed $M_{BH}$ - $sigma_{star}$ relation for our Type 1 AGNs, we estimate the black hole masses for the Type 2 AGNs and the inactive galaxies in our sample. In conclusion, we find that our sample of local luminous AGNs is consistent with the $M_{BH}$ - $sigma_{star}$ relation of lower luminosity AGNs and inactive galaxies, after correcting for dust extinction and the rotational contribution to the stellar velocity dispersion.
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