We propose a new evolutionary model of a supermassive black hole (SMBH) and a circumnuclear disk (CND), taking into account the mass-supply from a host galaxy and the physical states of CND. In the model, two distinct accretion modes depending on gravitational stability of the CND play a key role on accreting gas to a SMBH. (i) If the CMD is gravitationally unstable, energy feedback from supernovae (SNe) supports a geometrically thick, turbulent gas disk. The accretion in this mode is dominated by turbulent viscosity, and it is significantly larger than that in the mode (ii), i.e., the CMD is supported by gas pressure. Once the gas supply from the host is stopped, the high accretion phase ($\sim 0.01- 0.1 M_{\odot} {\rm yr}^{-1}$) changes to the low one (mode (ii), $\sim 10^{-4} M_{\odot} {\rm yr}^{-1}$), but there is a delay with $\sim 10^{8}$ yr. Through this evolution, the gas-rich CND turns into the gas poor stellar disk. We found that not all the gas supplied from the host galaxy accrete onto the SMBH even in the high accretion phase (mode (i)), because the part of gas is used to form stars. As a result, the final SMBH mass ($M_{\rm BH,final}$) is not proportional to the total gas mass supplied from the host galaxy ($M_{\rm sup}$); $M_{\rm BH,final}/M_{\rm sup}$ decreases with $M_{\rm sup}$.This would indicate that it is difficult to form a SMBH with $\sim 10^{9} M_{\odot}$ observed at high-$z$ QSOs. The evolution of the SMBH and CND would be related to the evolutionary tracks of different type of AGNs.Comment: 11 pages, 11 figures, accepted for publication in Ap

We report the finding of kiloparsec (kpc)-scale radio structures in three radio-loud narrow-line Seyfert 1 (NLS1) galaxies from the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) of the Very Large Array (VLA), which increases the number of known radio-loud NLS1s with kpc-scale structures to six, including two γ-ray emitting NLS1s (PMN J0948+0022 and 1H 0323+342) detected by the Fermi Gamma-ray Space Telescope. The detection rate of extended radio emissions in NLS1s is lower than that in broad-line active galactic nuclei (AGNs) with a statistical significance. We found both core-dominated (blazar-like) and lobe-dominated (radio-galaxy-like) radio structures in these six NLS1s, which can be understood in the framework of the unified scheme of radio-loud AGNs that considers radio galaxies as non-beamed parent populations of blazars. Five of the six NLS1s have (i) extended radio luminosities suggesting jet kinetic powers of 10 44 erg s −1 , which is sufficient to make jets escape from hosts' dense environments, (ii) black holes of 10 7 M ⊙ , which can generate the necessary jet powers from near-Eddington mass accretion, and (iii) two-sided radio structures at kpc scales, requiring expansion rates of ∼ 0.01c-0.3c and kinematic ages of 10 7 years. On the other hand, most typical NLS1s would be driven by black holes of 10 7 M ⊙ in a limited lifetime of ∼ 10 7 years. Hence the kpc-scale radio structures may originate in a small window of opportunity during the final stage of the NLS1 phase just before growing into broad-line AGNs.

We present ALMA Band 6 observations of the CO(2-1), HCN(3-2), and HCO + (3-2) lines in the nearby radio galaxy / brightest cluster galaxy (BCG) of NGC 1275 with the spatial resolution of ∼ 20 pc. In the previous observations, CO(2-1) emission was detected as radial filaments lying in the east-west direction. We resolved the inner filament and found that the filament cannot be represented by a simple infalling stream both morphologically and kinematically. The observed complex nature of the filament resembles the cold gas structure predicted by recent numerical simulations of cold chaotic accretion. A crude estimate suggests that the accretion rate of the cold gas can be higher than that of hot gas. Within the central 100 pc, we detected a rotational disk of the molecular gas whose mass is ∼ 10 8 M . This is the first evidence of the presence of massive cold gas disk on this spatial scale for BCGs. The disk rotation axis is approximately consistent with the axis of the radio jet on subpc scales. This probably suggests that the cold gas disk is physically connected to the innermost accretion disk which is responsible for jet launching. We also detected absorption features in the HCN(3-2) and HCO + (3-2) spectra against the radio continuum emission mostly radiated by ∼ 1.2-pc size jet. The absorption features are blue-shifted from the systemic velocity by ∼300-600 km s −1 , which suggests the presence of outflowing gas from the active galactic nucleus (AGN). We discuss the relation of the AGN feeding with cold accretion, the origin of blue-shifted absorption, and estimate of black hole mass using the molecular gas dynamics.

A B S T R A C TWe quantitatively scrutinize the effects of the radiation drag arising from the radiation fields in a galactic bulge in order to examine the possibility that the radiation drag could be an effective mechanism to extract angular momentum in a spheroidal system like a bulge and allow plenty of gas to accrete on to the galactic centre. For this purpose, we numerically solve the relativistic radiation hydrodynamical equation coupled with accurate radiative transfer, and quantitatively assess the radiation drag efficiency. As a result, we find that in an optically thick regime the radiation drag efficiency is sensitively dependent on the density distributions of the interstellar medium (ISM). The efficiency drops according to t 22T in an optically thick uniform ISM, where t T is the total optical depth of the dusty ISM, whereas the efficiency remains almost constant at a high level if the ISM is clumpy. Hence, if bulge formation begins with a star formation event in a clumpy ISM, the radiation drag will effectively work to remove the angular momentum and the accreted gas may form a supermassive black hole. As a natural consequence, this mechanism reproduces a putative linear relation between the mass of a supermassive black hole and the mass of a galactic bulge, although further detailed modelling for stellar evolution is required for a more precise prediction.

Based on the radiation hydrodynamical model for the black hole (BH) growth, incorporated with the chemical evolution of the early-type host galaxy, we construct the coevolution model of a QSO BH and the host galaxy. As a result, it is found that after a galactic wind epoch, the luminosity is shifted from the host-dominant phase to the AGN-dominant phase (QSO phase) in the timescale of a few 10 8 years. The former phase corresponds to the early stage of growing BH, and can be regarded as a "proto-QSO" phase. It has observable characteristic properties as follows: (1) The width of broad emission line is narrower than that of ordinary QSOs, and it is typically less than 1500km/s. (2) The BH-to-bulge mass ratio, M BH /M bulge , is in the range of 10 −5.3 − 10 −3.9 . (3) Host galaxies are bluer compared to QSO hosts, by about 0.5 magnitude in the colors of (B − V ) at the rest bands and (V − K ) at the observed bands, with assuming galaxy formation redshifts of z f = 3 − 5. (4) The metallicity of gas in galactic nuclei is ∼ 8Z ⊙ , and that of stars weighted by the host luminosity is ∼ 3Z ⊙ . (5) The central massive BH (≃ 10 7 M ⊙ ) is surrounded by a massive dusty disk (> 10 8 M ⊙ ), which may obscure the nucleus in the edge-on view and make a type 2 nucleus. By comparing these predictions with recent observations, radio galaxies are a possible candidate for proto-QSOs. Also, it is anticipated that the proto-QSO phase is preceded by an optically thick phase, which may correspond to ULIRGs. In this phase, M BH /M bulge is predicted to be much less than 10 −3 and grow with metallicity. Moreover, as precursors of ULIRGs, optically-thin star-forming galaxies are predicted. These may be in the assembly phase of Lyman break galaxies (LBGs) or Lyα emitters.