Abstract The evolution of the quasar luminosity function (QLF) is fundamental to understanding the cosmic evolution of black holes (BHs) through their accretion phases. In the era of the James Webb ...Space Telescope (JWST), Euclid, and Nancy Grace Roman Space Telescope, their unprecedented detection sensitivity and wide survey area can unveil the low-luminosity quasar and low-mass BH population, and provide new insights into quasar host galaxies. We present a theoretical model describing BH growth from initial seeding at z ≳ 20 to ∼ 4, incorporating the duration of accretion episodes, the distribution of Eddington ratios, and the mass dependency of BH accretion rates. By constraining the model parameters with the observed QLFs at 4 ≤ z ≤ 6 across a wide UV luminosity range, we find that the high-redshift BH population grows rapidly at z ≳ 6, and decelerates the pace in subsequent epochs. Toward lower redshifts ( z < 6), mass-dependent accretion inhibits the growth of high-mass BHs with M • > 10 8 M ⊙ , leading to mass saturation at M • ≳ 10 10 M ⊙ . We predict the BH mass function down to M • ∼ 10 6 M ⊙ for both unobscured and obscured quasar populations at 4 ≤ z ≤ 11, offering a benchmark for future observational tests. Our model accounts for the presence of both bright and faint quasars at z > 4, including those discovered by JWST. Furthermore, our findings suggest two distinct pathways for the early assembly of the BH–galaxy mass correlation: the population with a BH-to-stellar-mass ratio near the local value of M • / M ⋆ ≃ 5 × 10 −3 maintains proximity to the relation via moderate growth, while the population that begins to grow above the local relation becomes as overmassive as M • / M ⋆ ∼ 0.01–0.1 by z ∼ 6 via rapid mass accretion.
Abstract
The ultraluminous infrared galaxy IRAS 17208−0014 is a late-stage merger that hosts a buried active galactic nucleus (AGN). To investigate its nuclear structure, we performed ...high-spatial-resolution ( ∼ 0.″04 ∼ 32 pc) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 9 (∼450
μ
m or ∼660 GHz), along with near-infrared AKARI spectroscopy in 2.5–5.0
μ
m. The Band 9 dust continuum peaks at the AGN location, and toward this position CO(
J
= 6 − 5) and CS(
J
= 14 − 13) are detected in absorption. Comparison with nonlocal thermal equilibrium calculations indicates that, within the central beam (
r
∼ 20 pc), there exists a concentrated component that is dense (10
7
cm
−3
) and warm (>200 K) and has a large column density (
N
H
2
>
10
23
cm
−
2
). The AKARI spectrum shows deep and broad CO rovibrational absorption at 4.67
μ
m. Its band profile is well reproduced with a similarly dense and large column but hotter (∼1000 K) gas. The region observed through absorption in the near-infrared is highly likely in the nuclear direction, as in the submillimeter, but with a narrower beam including a region closer to the nucleus. The central component is considered to possess a hot structure where vibrationally excited HCN emission originates. The most plausible heating source for the gas is X-rays from the AGN. The AKARI spectrum does not show other AGN signs in 2.5–4
μ
m, but this absence may be usual for AGNs buried in a hot mid-infrared core. Further, based on our ALMA observations, we relate the various nuclear structures of IRAS 17208−0014 that have been proposed in the literature.
We used the Atacama Large Millimeter/submillimeter Array to map 12CO(J = 1-0), 12CO(J = 2-1), 12CO(J = 3-2), 13CO(J = 2-1), and C i(3P1-3P0) emission lines around the type 1 active galactic nucleus ...(AGN) of NGC 7469 (z = 0.0164) at ∼100 pc resolutions. The CO lines are bright in both the circumnuclear disk (central ∼300 pc) and the surrounding starburst (SB) ring (∼1 kpc diameter), with two bright peaks on either side of the AGN. By contrast, the C i(3P1-3P0) line is strongly peaked on the AGN. Consequently, the brightness temperature ratio of C i(3P1-3P0) to 13CO(2-1) is ∼20 at the AGN, as compared to ∼2 in the SB ring. Our local thermodynamic equilibrium (LTE) and non-LTE models indicate that the enhanced line ratios (or C i enhancement) are due to an elevated C0/CO abundance ratio (∼3-10) and temperature (∼100-500 K) around the AGN as compared to the SB ring (abundance ratio ∼1, temperature 100 K), which accords with the picture of the X-ray-dominated region. Based on dynamical modelings, we also provide CO(1-0)-to- and C i(3P1-3P0)-to-molecular mass conversion factors at the central ∼100 pc of this AGN as CO = 4.1 and C i = 4.4 M (K km s−1 pc2)−1, respectively. Our results suggest that the C i enhancement is potentially a good marker of AGNs that could be used in a new submillimeter diagnostic method toward dusty environments.
Abstract
We present Atacama Large Millimeter/submillimeter Array C
ii
158
μ
m line and underlying far-infrared (FIR) continuum emission observations (0.″70 × 0.″56 resolution) toward HSC ...J124353.93+010038.5 (J1243+0100) at
z
= 7.07, the only low-luminosity (
M
1450
> −25 mag) quasar currently known at
z
> 7. The FIR continuum is bright (1.52 mJy) and resolved with a total luminosity of
L
FIR
= 3.5 × 10
12
L
⊙
. The spatially extended component is responsible for ∼40% of the emission. The area-integrated C
ii
spectrum shows a broad wing (FWHM = 997 km s
−1
,
L
C
ii
= 1.2 × 10
9
L
⊙
), as well as a bright core (FWHM = 235 km s
−1
,
L
C
ii
= 1.9 × 10
9
L
⊙
). This wing is the first detection of a galactic-scale quasar-driven outflow (atomic outflow rate >447
M
⊙
yr
−1
) at
z
> 7. The estimated large mass-loading factor of the total outflow (e.g., ≳9 relative to the C
ii
-based star formation rate) suggests that this outflow will soon quench the star formation of the host. The core gas dynamics are governed by rotation, with a rotation curve suggestive of a compact bulge (∼3.3 × 10
10
M
⊙
), although it is not yet spatially resolved. Finally, we found that J1243+0100 has a black hole mass–to–dynamical mass (and –to–bulge mass) ratio of ∼0.4% (∼1%), consistent with the local value within the uncertainties. Our results therefore suggest that the black hole–host coevolution relation is already in place at
z
∼ 7 for this object.
We report spatial distributions of the Fe-K line at 6.4 keV and the CO(J = 2-1) line at 230.538 GHz in NGC 2110, which are, respectively, revealed by Chandra and Atacama Large ...Millimeter/submillimeter Array (ALMA) at 0 5. A Chandra 6.2-6.5 keV to 3.0-6.0 keV image suggests that the Fe-K emission extends preferentially in a northwest to southeast direction out to 3″, or ∼500 pc, on each side. Spatially resolved spectral analyses support this by finding significant Fe-K emission lines only in the northwest and southeast regions. Moreover, their equivalent widths are found to be ∼1.5 keV, indicative for the fluorescence by nuclear X-ray irradiation as the physical origin. By contrast, CO(J = 2-1) emission is weak therein. For quantitative discussion, we derive ionization parameters by following an X-ray dominated region (XDR) model. We then find them high enough to interpret the weakness as the result of X-ray dissociation of CO and/or H2. Another possibility also remains that CO molecules follow a superthermal distribution, resulting in brighter emission in higher-J lines. Further follow-up observations are encouraged to draw a conclusion on what predominantly changes the interstellar matter properties and whether the X-ray irradiation eventually affects the surrounding star formation as active galactic nucleus (AGN) feedback.
Abstract
H1821+643 is the most X-ray luminous nonbeamed active galactic nucleus (AGN) of
L
14–150 keV
= 5.2 × 10
45
erg s
−1
in the Swift/Burst Alert Telescope (BAT) ultrahard X-ray survey, and it is ...also a hyperluminous infrared (IR) galaxy
L
IR
= 10
13.2
L
⊙
residing in the center of a massive galaxy cluster, which is a unique environment achieving the rapid mass assembly of black holes (BH) and host galaxies in the local universe. We decompose the X-ray to IR spectral energy distribution (SED) into the AGN and starburst component using the SED-fitting tool
CIGALE
-2022.0 and show that H1821+643 consumes a large amount of cold gas (
M
̇
con
) with star formation rate of
log
(
SFR
/
M
⊙
yr
−
1
)
=
3.01
±
0.04
and BH accretion rate of
log
(
M
̇
BH
/
M
⊙
yr
−
1
)
=
1.20
±
0.05
. This high
M
̇
con
is larger than the cooling rate (
M
̇
cool
) of the intracluster medium,
M
̇
con
/
M
̇
cool
≳
1
, which is 1 to 2 orders of magnitude higher than the typical value of other systems, indicating that H1821+643 provides the unique and extreme environment of rapid gas consumption. We also show that H1821+643 has an efficient cooling path achieving from 10
7
to 10
2
K thanks to O
i
63
μ
m, which is a main coolant in low temperature range (10
4
to 10
2
K) with a cooling rate of
M
̇
cool
=
3.2
×
10
5
M
⊙
yr
−
1
, and the star-forming region extends over 40 kpc scale.
Abstract
To investigate the role of active galactic nucleus (AGN) X-ray irradiation on the interstellar medium (ISM), we systematically analyzed Chandra and Atacama Large Millimeter/submillimeter ...Array CO (
J
= 2–1) data for 26 hard X-ray (>10 keV) selected AGNs at redshifts below 0.05. While Chandra unveils the distribution of X-ray-irradiated gas via Fe-K
α
emission, the CO (
J
= 2–1) observations reveal that of cold molecular gas. At high resolutions ≲1″, we derive Fe-K
α
and CO (
J
= 2–1) maps for the nuclear 2″ region and for the external annular region of 2″–4″, where 2″ is ∼100–600 pc for most of our AGNs. First, focusing on the external regions, we find the Fe-K
α
emission for six AGNs above 2
σ
. Their large equivalent widths (≳1 keV) suggest a fluorescent process as their origin. Moreover, by comparing the 6–7 keV/3–6 keV ratio, as a proxy of Fe-K
α
, and CO (
J
= 2–1) images for three AGNs with the highest significant Fe-K
α
detections, we find a possible spatial separation. These suggest the presence of X-ray-irradiated ISM and the change in the ISM properties. Next, examining the nuclear regions, we find that (1) the 20–50 keV luminosity increases with the CO (
J
= 2–1) luminosity; (2) the ratio of CO (
J
= 2–1)/HCN (
J
= 1–0) luminosities increases with 20–50 keV luminosity, suggesting a decrease in the dense gas fraction with X-ray luminosity; and (3) the Fe-K
α
-to-X-ray continuum luminosity ratio decreases with the molecular gas mass. This may be explained by a negative AGN feedback scenario: the mass accretion rate increases with gas mass, and simultaneously, the AGN evaporates a portion of the gas, which possibly affects star formation.
Abstract
Recent developments in (sub)millimeter facilities have drastically changed the amount of information obtained from extragalactic spectral scans. In this paper, we present a feature ...extraction technique using principal component analysis (PCA) applied to arcsecond-resolution (1.″0–2.″0 = 72–144 pc) spectral scan data sets for the nearby type-2 Seyfert galaxy NGC 1068, using Band 3 of the Atacama Large Millimeter/submillimeter Array. We apply PCA to 16 well-detected molecular line intensity maps convolved to a common 150 pc resolution. In addition, we include the S
iii
/S
ii
line ratio and C
i
3
P
1
–
3
P
0
maps in the literature, both of whose distributions show a remarkable resemblance to that of a kiloparsec-scale biconical outflow from the central active galactic nucleus. We identify two prominent features: (1) central concentration at the circumnuclear disk (CND) and (2) two peaks across the center that coincide with the biconical outflow peaks. The concentrated molecular lines in the CND are mostly high-dipole molecules (e.g., H
13
CN, HC
3
N, and HCN). Line emissions from molecules known to be enhanced in an irradiated interstellar medium, CN, C
2
H, and HNC, show similar concentrations and extended components along the bicone, suggesting that molecule dissociation is a dominant chemical effect of the cold molecular outflow of this galaxy. Although further investigation should be made, this scenario is consistent with the faintness or absence of emission lines from CO isotopologues, CH
3
OH, and N
2
H
+
in the outflow, which are easily destroyed by dissociating photons and electrons.
ABSTRACT Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(4-3) and/or HCN(4-3)/CS(7-6) integrated intensity ratios in ...circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO+ and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even 10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral-neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.
ABSTRACT
We present a supermassive black hole (SMBH) mass measurement in the Seyfert 1 galaxy NGC 7469 using Atacama Large Millimeter/submillimeter Array (ALMA) observations of the atomic-CI(1–0) and ...molecular-12CO(1–0) emission lines at the spatial resolution of ≈0${_{.}^{\prime\prime}}$3 (or ≈100 pc). These emissions reveal that NGC 7469 hosts a circumnuclear gas disc (CND) with a ring-like structure and a two-arm/bi-symmetric spiral pattern within it, surrounded by a starbursting ring. The CND has a relatively low σgas/V ≈ 0.35 (r ≲ 0${_{.}^{\prime\prime}}$5) and ≈0.19 (r > 0${_{.}^{\prime\prime}}$5), suggesting that the gas is dynamically settled and suitable for dynamically deriving the mass of its central source. As is expected from X-ray dominated region (XDR) effects that dramatically increase an atomic carbon abundance by dissociating CO molecules, we suggest that the atomic CI(1–0) emission is a better probe of SMBH masses than CO emission in active galactic nuclei (AGNs). Our dynamical model using the CI(1–0) kinematics yields a $M_{\rm BH}=1.78^{+2.69}_{-1.10}\times 10^7$ M⊙ and $M/L_{\rm F547M}=2.25^{+0.40}_{-0.43}$ (M⊙/L⊙). The model using the 12CO(1–0) kinematics also gives a consistent MBH with a larger uncertainty, up to an order of magnitude, i.e. $M_{\rm BH}=1.60^{+11.52}_{-1.45}\times 10^7$ M⊙. This newly dynamical MBH is ≈2 times higher than the mass determined from the reverberation mapped (RM) method using emissions arising in the unresolved broad-line region (BLR). Given this new MBH, we are able to constrain the specific RM dimensionless scaling factor of $f=7.2^{+4.2}_{-3.4}$ for the AGN BLR in NGC 7469. The gas within the unresolved BLR thus has a Keplerian virial velocity component and the inclination of $i\approx {11.0^\circ }_{-2.5}^{+2.2}$, confirming its face-on orientation in a Seyfert 1 AGN by assuming a geometrically thin BLR model.
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