ABSTRACT We present a positive correlation between the mass of dense molecular gas ( ) of ∼100 pc scale circumnuclear disks (CNDs) and the black hole mass accretion rate ( ) in a total of 10 Seyfert ...galaxies, based on data compiled from the literature and an archive (median aperture θmed = 220 pc). A typical of CNDs is 107-8 , 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 revealed previously. Moreover, the 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 ( ) is consumed as . However, agrees well with the total nuclear mass flow rate (i.e., + 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.
In this study, we investigate the line emissions from cold molecular gas based on our previous "radiation-driven fountain model," which reliably explains the spectral energy distribution of the ...nearest type 2 Seyfert galaxy, the Circinus galaxy. Using a snapshot of the best-fit radiation-hydrodynamic model for the central pc, in which non-equilibrium X-ray-dominated region chemistry is solved, we conduct post-processed non-local thermodynamic equilibrium radiation transfer simulations for the CO lines. We obtain a spectral line energy distribution with a peak around , and its distribution suggests that the lines are not thermalized. However, for a given line of sight, the optical depth distribution is highly non-uniform between and . The CO-to-H2 conversion factor ( ), which can be directly obtained from the results and is not a constant, depends strongly on the integrated intensity and differs from the fiducial value for local objects. exhibits a large dispersion of more than one order of magnitude, reflecting the non-uniform internal structure of a "torus." In addition, we found that the physical conditions differ between grid cells on a scale of a few parsecs along the observed lines of sight; therefore, a specific observed line ratio does not necessarily represent a single physical state of the interstellar medium.
We present the results of our ALMA observations of 11 (ultra)luminous infrared galaxies ((U)LIRGs) at J = 4-3 of HCN, HCO+, and HNC and J = 3-2 of HNC. This is an extension of our previously ...published HCN and HCO+ J = 3-2 observations to multiple rotational J-transitions of multiple molecules, to investigate how molecular emission line flux ratios vary at different J-transitions. We confirm that ultraluminous infrared galaxies (ULIRGs) that contain or may contain luminous obscured active galactic nuclei (AGNs) tend to show higher HCN-to-HCO+ flux ratios than starburst galaxies, both at J = 4-3 and J = 3-2. For selected HCN-flux-enhanced AGN-important ULIRGs, our isotopologue H13CN, H13CO+, and HN13C J = 3-2 line observations suggest a higher abundance of HCN than HCO+ and HNC, which is interpreted to be primarily responsible for the elevated HCN flux in AGN-important galaxies. For such sources, the intrinsic HCN-to-HCO+ flux ratios after line opacity correction will be higher than the observed ratios, making the separation between AGNs and starbursts even larger. The signature of the vibrationally excited (v2 = 1f) HCN J = 4-3 emission line is seen in one ULIRG, IRAS 12112−0305 NE. P Cygni profiles are detected in the HCO+ J = 4-3 and J = 3-2 lines toward IRAS 15250+3609, with an estimated molecular outflow rate of ∼250-750 M yr−1. The SiO J = 6-5 line also exhibits a P Cygni profile in IRAS 12112+0305 NE, suggesting the presence of shocked outflow activity. Shock tracers are detected in many sources, suggesting ubiquitous shock activity in the nearby ULIRG population.
We report on the relation between the mass of supermassive black holes (SMBHs; ) and that of hosting dark matter halos ( ) for 49 z ∼ 6 quasi-stellar objects (QSOs) with C ii158 m velocity-width ...measurements. Here, we estimate assuming that the rotation velocity from is equal to the circular velocity of the halo; we have tested this procedure using z ∼ 3 QSOs that also have clustering-based estimates. We find that a vast majority of the z ∼ 6 SMBHs are more massive than expected from the local - relation, with one-third of the sample by factors 102. The median mass ratio of the sample, , means that 0.4% of the baryons in halos are locked up in SMBHs. The mass growth rates of our SMBHs amount to ∼10% of the star formation rates (SFRs), or ∼1% of the mean baryon accretion rates, of the hosting galaxies. A large fraction of the hosting galaxies are consistent with average galaxies in terms of SFR and perhaps of stellar mass and size. Our study indicates that the growth of SMBHs ( ) in luminous z ∼ 6 QSOs greatly precedes that of hosting halos owing to efficient gas accretion even under normal star formation activities, although we cannot rule out the possibility that undetected SMBHs have local ratios. This preceding growth is in contrast to much milder evolution of the stellar-to-halo mass ratio.
UltraFast Outflows (UFOs), seen as X-ray blueshifted absorption lines in active galactic nuclei (AGNs), are considered to be a key mechanism for AGN feedback. In this scenario, UFO kinetic energy is ...transferred into the cold and extended molecular outflow observed at the millimeter/submillimeter wavelength, which blows away the gas and suppresses star formation and accretion onto the central black hole (BH). However, the energy transfer between the inner UFO and the outer molecular outflow has not yet been fully studied mainly due to the limited sample. In this paper, we perform a comparison of their kinetic energy using the millimeter/submillimeter published data and the X-ray archival data. Among 14 Seyfert galaxies whose molecular outflows are detected in the Institut de RAdioastronomie Millimétrique/Plateau de Bure Interferometer data, 8 targets are bright enough to perform spectral fitting in X-ray, and we have detected UFO absorption lines in 6 targets with a 90% significance level, using XMM-Newton and Suzaku satellites. The time-averaged UFO kinetic energy was derived from the spectral fitting. As a result, we have found that the energy-transfer rate (kinetic energy ratio of the molecular outflow to the UFO) ranges from ∼7 × 10−3 to ∼1, and has a negative correlation with the BH mass, which shows that the AGN feedback is more efficient in the lower mass BHs. This tendency is consistent with the theoretical prediction that the cooling timescale of the outflowing gas becomes longer than the flow timescale when the BH mass is smaller.
We present the results of our ALMA Cycle 4 high-spatial-resolution (0 04-0 07) observations, at HCN J = 3-2 and HCO+ J = 3-2 lines, of the nucleus of NGC 1068, the nearby prototypical type 2 active ...galactic nucleus (AGN). Our previous ALMA observations identified the compact emission of these lines at the putative location of the torus around a mass-accreting supermassive black hole. We now report that we have detected the rotation of this compact emission, with the eastern and western sides being redshifted and blueshifted, respectively. Unlike the previously reported CO J = 6-5 emission, both the morphological and dynamical alignments of the HCN J = 3-2 and HCO+ J = 3-2 emission are roughly along the east-west direction (i.e., the expected torus direction), suggesting that these molecular lines are better probes of a rotating dense molecular gas component in the torus. The western part of the torus exhibits larger velocity dispersion and stronger emission in the HCN J = 3-2 and HCO+ J = 3-2 lines than the eastern part, revealing a highly inhomogeneous molecular torus. The dense molecular gas in the torus and that of the host galaxy at 0 5-2 0 from the AGN along the torus direction are found to be counter-rotating, suggesting an external process happened in the past at the NGC 1068 nucleus.
Abstract
We report on a study of X-ray-irradiated gas in the central ∼100 pc of the Circinus galaxy, which hosts a Compton-thick active galactic nucleus (AGN), at 10 pc resolution using Chandra and ...ALMA. Based on ∼200 ks Chandra/ACIS-S data, we created an image of the Fe Kα line at 6.4 keV, tracing X-ray-irradiated dense gas. The ALMA data in Bands 6 (∼270 GHz) and 7 (∼350 GHz) cover five molecular lines: CO(J = 3–2), HCN(J = 3–2), HCN(J = 4–3), HCO+(J = 3–2), and HCO+(J = 4–3). The detailed spatial distribution of dense molecular gas was revealed, and compared to the iron line image. The molecular gas emission appeared faint in regions with bright iron emission. Motivated by this, we quantitatively discuss the possibility that the molecular gas is efficiently dissociated by AGN X-ray irradiation (i.e., creating an X-ray-dominated region). Based on a non-local thermodynamic equilibrium model, we constrained the molecular gas densities and found that they are as low as interpreted by X-ray dissociation. Furthermore, judging from inactive star formation reported in the literature, we suggest that the X-ray emission has the potential to suppress star formation, particularly in the proximity of the AGN.
Abstract
We report the results of Atacama Large Millimeter/submillimeter Array (ALMA) 1–2 kpc resolution, three rotational transition-line (
J
= 2–1,
J
= 3–2, and
J
= 4–3) observations of multiple ...dense molecular gas tracers (HCN, HCO
+
, and HNC) for 10 nearby (ultra)luminous infrared galaxies ((U)LIRGs). Following the matching of beam sizes to 1–2 kpc for each (U)LIRG, the high-
J
-to-low-
J
transition-line flux ratios of each molecule and the emission-line flux ratios of different molecules at each
J
transition are derived. We conduct RADEX non-LTE model calculations and find that, under a wide range of gas density and kinetic temperature, the observed HCN-to-HCO
+
flux ratios in the overall (U)LIRGs are naturally reproduced with enhanced HCN abundance compared to HCO
+
. Thereafter, molecular gas properties are constrained primarily through the use of HCN and HCO
+
data and the adoption of fiducial values for the HCO
+
column density and HCN-to-HCO
+
abundance ratio. We quantitatively confirm the following: (i) molecular gas at the (U)LIRGs’ nuclei is dense (≳10
3–4
cm
−3
) and warm (≳100 K), (ii) the molecular gas density and temperature in nine ULIRGs’ nuclei are significantly higher than those of one LIRG’s nucleus, (iii) molecular gas in starburst-dominated sources tends to be less dense and cooler than ULIRGs with luminous AGN signatures. For six selected sources, we also apply a Bayesian approach by freeing all parameters and support the above main results. Our ALMA 1–2 kpc resolution, multiple transition-line data of multiple molecules are a very powerful tool for scrutinizing the properties of molecular gas concentrated around luminous energy sources in nearby (U)LIRGs’ nuclei.
We present deep near-infrared spectroscopy of six quasars at 6.1 ≤ z ≤ 6.7 with Very Large Telescope/X-Shooter and Gemini-N/GNIRS. Our objects, originally discovered through a wide-field optical ...survey with the Hyper Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP), have the lowest luminosities (−25.5 mag ≤ M1450 ≤ −23.1 mag) of the z > 5.8 quasars with measured black hole (BH) masses. From single-epoch mass measurements based on Mg ii λ2798, we find a wide range in BH masses, from MBH = 107.6 to 109.3 M . The Eddington ratios Lbol/LEdd range from 0.16 to 1.1, but the majority of the HSC quasars are powered by MBH ∼ 109 M supermassive black holes (SMBHs) accreting at sub-Eddington rates. The Eddington ratio distribution of the HSC quasars is inclined to lower accretion rates than those of Willott et al., who measured the BH masses for similarly faint z ∼ 6 quasars. This suggests that the global Eddington ratio distribution is wider than has previously been thought. The presence of MBH ∼ 109 M SMBHs at z ∼ 6 cannot be explained with constant sub-Eddington accretion from stellar remnant seed BHs. Therefore, we may be witnessing the first buildup of the most massive BHs in the first billion years of the universe, the accretion activity of which is transforming from active growth to a quiescent phase. Measurements of a larger complete sample of z 6 low-luminosity quasars, as well as deeper observations with future facilities, will enable us to better understand the early SMBH growth in the reionization epoch.
ABSTRACT We present the results of our ALMA observations of three active galactic nucleus (AGN)-dominated nuclei in optical Seyfert 1 galaxies (NGC 7469, I Zw 1, and IC 4329 A) and eleven luminous ...infrared galaxies (LIRGs) with various levels of infrared estimated energetic contributions by AGNs at the HCN and HCO+ J = 3 − 2 emission lines. The HCN and HCO+ J = 3 − 2 emission lines are clearly detected at the main nuclei of all sources, except for IC 4329 A. The vibrationally excited (v2 = 1f) HCN J = 3 − 2 and HCO+ J = 3 − 2 emission lines are simultaneously covered, and HCN v2 = 1f J = 3 − 2 emission line signatures are seen in the main nuclei of two LIRGs, IRAS 12112+0305 and IRAS 22491-1808, neither of which shows clear buried AGN signatures in the infrared. If the vibrational excitation is dominated by infrared radiative pumping, through the absorption of infrared 14 m photons, primarily originating from AGN-heated hot dust emission, then these two LIRGs may contain infrared-elusive, but (sub)millimeter-detectable, extremely deeply buried AGNs. These vibrationally excited emission lines are not detected in the three AGN-dominated optical Seyfert 1 nuclei. However, the observed HCN v2 = 1f to v = 0 flux ratios in these optical Seyferts are still consistent with the intrinsic flux ratios in LIRGs with detectable HCN v2 = 1f emission lines. The observed HCN-to-HCO+ J = 3 − 2 flux ratios tend to be higher in galactic nuclei with luminous AGN signatures compared with starburst-dominated regions, as previously seen at J = 1 − 0 and J = 4 − 3.
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