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We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were serendipitously discovered from the deep multiband imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The quasars, HSC J121503.42−014858.7 (C1) and HSC J121503.55−014859.3 (C2), both have luminous (>10 ^43 erg s ^−1 ) Ly α emission with a clear broad component (full width at half maximum >1000 km s ^−1 ). The rest-frame ultraviolet (UV) absolute magnitudes are M _1450 = − 23.106 ± 0.017 (C1) and −22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })=8.1\pm 0.3$ in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.

Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the coevolution of black holes and galaxies. We present the angular correlation function between an AGN sample selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical photometry and Wide-field Infrared Survey Explorer mid-IR photometry and a luminous red galaxy (LRG) sample from HSC-SSP. We investigate AGN clustering strength as a function of luminosity and spectral features across three independent HSC fields totaling ∼600 deg ^2 , for z ∈ 0.6 −1.2 and AGN with L _6 _ μ _m > 3 × 10 ^44 erg s ^−1 . There are ∼28,500 AGN and ∼1.5 million LRGs in our primary analysis. We determine the average halo mass for the full AGN sample ( M _h ≈ 10 ^12.9 h ^−1 M _⊙ ), and note that it does not evolve significantly as a function of redshift (over this narrow range) or luminosity. We find that, on average, unobscured AGN ( M _h ≈ 10 ^13.3 h ^−1 M _⊙ ) occupy ∼4.5× more massive halos than obscured AGN ( M _h ≈ 10 ^12.6 h ^−1 M _⊙ ), at 5 σ statistical significance using 1D uncertainties, and at 3 σ using the full covariance matrix, suggesting a physical difference between unobscured and obscured AGN, beyond the line-of-sight viewing angle. Furthermore, we find evidence for a halo mass dependence on reddening level within the Type I AGN population, which could support the existence of a dust-obscured phase. However, we also find that quite small systematic shifts in the redshift distributions of the AGN sample could explain current and previously observed differences in M _h .

We present Atacama Large Millimeter/submillimeter Array [C ii ] 158 μ m line and underlying far-IR continuum emission observations (0.″57 × 0.″46 resolution) toward a quasar–quasar pair system recently discovered at z = 6.05. The quasar nuclei (C1 and C2) are faint ( M _1450 ≳ −23 mag), but we detect very bright [C ii ] emission bridging the 12 kpc between the two objects and extending beyond them (total luminosity L _[C _ii _] ≃ 6 × 10 ^9 L _⊙ ). The [C ii ]-based total star formation rate of the system is ∼550 M _⊙ yr ^−1 (the IR-based dust-obscured star formation is ∼100 M _⊙ yr ^−1 ), with a [C ii ]-based total gas mass of ∼10 ^11 M _⊙ . The dynamical masses of the two galaxies are large (∼9 × 10 ^10 M _⊙ for C1 and ∼5 × 10 ^10 M _⊙ for C2). There is a smooth velocity gradient in [C ii ], indicating that these quasars are a tidally interacting system. We identified a dynamically distinct, fast-[C ii ] component around C1: detailed inspection of the line spectrum there reveals the presence of a broad-wing component, which we interpret as the indication of fast outflows with a velocity of ∼600 km s ^−1 . The expected mass-loading factor of the outflows, after accounting for multiphase gas, is ≳2 − 3, which is intermediate between AGN-driven and starburst-driven outflows. Hydrodynamic simulations in the literature predict that this pair will evolve to a luminous ( M _1450 ≲ −26 mag), starbursting (≳1000 M _⊙ yr ^−1 ) quasar after coalescence, one of the most extreme populations in the early Universe.

We present Atacama Large Millimeter/submillimeter Array observations of the [C ii ] 158 μ m line and the underlying continuum emission of TN J0924−2201, which is one of the most distant known radio galaxies at z > 5. The [C ii ] line and 1 mm continuum emission are detected at the host galaxy. The systemic redshift derived from the [C ii ] line is z _[C _II _] = 5.1736 ± 0.0002, indicating that the Ly α line is redshifted by a velocity of 1035 ± 10 km s ^−1 , marking the largest velocity offset between the [C ii ] and Ly α lines recorded at z > 5 to date. In the central region of the host galaxy, we identify a redshifted substructure of [C ii ] with a velocity of 702 ± 17 km s ^−1 , which is close to the C iv line with a velocity of 500 ± 10 km s ^−1 . The position and the velocity offsets align with a model of an outflowing shell structure, consistent with the large velocity offset of Ly α . The nondetection of [C ii ] and dust emission from the three CO(1–0)-detected companions indicates their different nature compared to dwarf galaxies, based on the photodissociation region model. Given their large velocity of ∼1500 km s ^−1 , outflowing molecular clouds induced by the active galactic nucleus are the most plausible interpretation, and they may exceed the escape velocity of a 10 ^13 M _⊙ halo. These results suggest that TN J0924−2201, with ongoing and fossil large-scale outflows, is in a distinctive phase of removing molecular gas from a central massive galaxy in an overdense region in the early Universe. A dusty H i absorber at the host galaxy is an alternative interpretation.

We examine the local density environments around 67 quasars at z ∼ 3 by combining the imaging data of Hyper Suprime-Cam Subaru Strategic Program and Canada–France–Hawaii Telescope Large Area U -band Deep Survey over about 20 deg ^2 . Our measurements exploit U -dropout galaxies in the vicinities of quasars taken from the Sloan Digital Sky Survey. We find that the quasars have an indistinguishable surrounding density distribution from the U -dropout galaxies and that three quasars are associated with protocluster candidates within a projected separation of 3′. According to a halo evolutionary model, our results suggest that quasars at this epoch occupy haloes with a typical mass of ${1.3}_{-0.9}^{+1.4}\times {10}^{13}{h}^{-1}{{M}}_{\odot }$ . We also investigate the dependence of the local galaxy overdensity on ultraviolet (UV) luminosities, black hole masses, and proximity zone sizes of the quasars, but no statistically significant correlation was found. Finally, we find that the local density of faint U -dropout galaxies are lower than that of bright U -dropout galaxies within a projected distance of 0.51 ± 0.05 physical Mpc, where the quasar UV radiation is 30 times more intense than background UV radiation. We argue that photoevaporation may suppress galaxy formation at short distances where the quasar UV intensity is strong, even in massive haloes.

We present confusion-limited SCUBA-2 450 μ m observations in the COSMOS-CANDELS region as part of the James Clerk Maxwell Telescope Large Program SCUBA-2 Ultra Deep Imaging EAO Survey. Our maps at 450 and 850 μ m cover an area of 450 arcmin ^2 . We achieved instrumental noise levels of σ _450 = 0.59 mJy beam ^−1 and σ _850 = 0.09 mJy beam ^−1 in the deepest area of each map. The corresponding confusion noise levels are estimated to be 0.65 and 0.36 mJy beam ^−1 . Above the 4 σ (3.5 σ ) threshold, we detected 360 (479) sources at 450 μ m and 237 (314) sources at 850 μ m. We derive the deepest blank-field number counts at 450 μ m, covering the flux-density range of 2–43 mJy. These are in agreement with other SCUBA-2 blank-field and lensing-cluster observations but are lower than various model counts. We compare the counts with those in other fields and find that the field-to-field variance observed at 450 μ m at the $R=6^{\prime} $ scale is consistent with Poisson noise, so there is no evidence of strong 2D clustering at this scale. Additionally, we derive the integrated surface brightness at 450 μ m down to 2.1 mJy to be ${57.3}_{-6.2}^{+1.0}$ Jy deg ^−2 , contributing to 41% ± 4% of the 450 μ m extragalactic background light (EBL) measured by Cosmic Background Explorer and Planck. Our results suggest that the 450 μ m EBL may be fully resolved at ${0.08}_{-0.08}^{+0.09}$ mJy, which extremely deep lensing-cluster observations and next-generation submillimeter instruments with large aperture sizes may be able to achieve.

We report the distribution of black hole (BH) masses and Eddingont ratios estimated for a sample of 131 low luminosity quasars in the early cosmic epoch (5.6 < z < 7.0). Our work is based on the Subaru High- z Exploration of Low-Luminosity Quasars (SHELLQs) project, which has constructed a low luminosity quasar sample down to M _1450 ∼ − 21 mag, exploiting the survey data of Hyper Suprime-Cam installed on Subaru Telescope. The discovery spectra of these quasars are limited to the rest-frame wavelengths of ∼1200–1400 Å, which contain no emission lines that can be used as BH mass estimators. In order to overcome this problem, we made use of low- z counterpart spectra from the Sloan Digital Sky Survey, which are spectrally matched to the high- z spectra in overlapping wavelengths. We then combined the C iv emission line widths of the counterparts with the continuum luminosity from the SHELLQs data to estimate BH masses. The resulting BH mass distribution has a range of ∼10 ^7–10 M _⊙ , with most of the quasars having BH masses ∼10 ^8 M _⊙ with sub-Eddington accretion. The present study provides not only a new insight into normal quasars in the reionization epoch, but also a new promising way to estimate BH masses of high- z quasars without near-infrared spectroscopy.

Herein, we present the statistical properties of active galactic nuclei (AGNs) for approximately 1 million member galaxies of galaxy groups and clusters with 0.1 < cluster redshift ( z _cl ) < 1.4 selected using the Subaru Hyper Suprime-Cam, the so-called CAMIRA clusters. In this research, we focused on the AGN power fraction ( f _AGN ), which is defined as the proportion of the contribution of AGNs to the total infrared (IR) luminosity, L _IR (AGN)/ L _IR , and examined how f _AGN depends on (i) z _cl and (ii) the distance from the cluster center. We compiled multiwavelength data using the ultraviolet–mid-IR range. Moreover, we performed spectral energy distribution fits to determine f _AGN using the CIGALE code with the SKIRTOR AGN model. We found that (i) the value of f _AGN in the CAMIRA clusters is positively correlated with z _cl , with the correlation slope being steeper than that for field galaxies, and (ii) f _AGN exhibits a high value at the cluster outskirts. These results indicate that the emergence of the AGN population depends on the redshift and environment and that galaxy groups and clusters at high redshifts are important in AGN evolution. Additionally, we demonstrated that cluster–cluster mergers may enhance AGN activity at the outskirts of particularly massive galaxy clusters. Our findings are consistent with a related study on the CAMIRA clusters that was based on the AGN number fraction.

We study “buried” active galactic nuclei (AGNs) almost fully covered by circumnuclear material in ultra/luminous infrared galaxies (U/LIRGs), which show weak ionized lines from narrow-line regions. Employing an indicator of a [O iv ] 25.89 or [Ne v ] 14.32 μ m line to 12 μ m AGN luminosity ratio, we find 17 buried AGN candidates that are [O iv ]-weak ( L _[O _IV _] / L _12,AGN ≤ −3.0) or [Ne v ]-weak ( L _[Ne V] / L _12,AGN ≤ −3.4) among 30 AGNs in local U/LIRGs. For the [O iv ]-weak AGNs, we estimate their covering fractions of Compton-thick (CT; N _H ≥ 10 ^24 cm ^−2 ) material with an X-ray clumpy torus model to be ${f}_{\mathrm{CT}}^{(\mathrm{spec})}=0.55\pm 0.19$ on average. This value is consistent with the fraction of CT AGNs ( ${f}_{\mathrm{CT}}^{(\mathrm{stat})}=53 \% \pm 12 \% $ ) among the [O iv ]-weak AGNs in U/LIRGs and much larger than that in Swift/Burst Alert Telescope (BAT) AGNs (23% ± 6%). The fraction of [O iv ]-weak AGNs increases from ${27}_{-10}^{+13} \% $ (early) to ${66}_{-12}^{+10} \% $ (late mergers). Similar results are obtained with the [Ne v ] line. The [O iv ]- or [Ne v ]-weak AGNs in late mergers show larger N _H and Eddington ratios ( λ _Edd ) than those of the Swift/BAT AGNs, and the largest N _H is ≳10 ^25 cm ^−2 at $\mathrm{log}{\lambda }_{\mathrm{Edd}}\sim -1$ , close to the effective Eddington limit for CT material. These suggest that (1) the circumnuclear material in buried AGNs is regulated by the radiation force from high- λ _Edd AGNs on the CT obscurers, and (2) their dense material with large ${f}_{\mathrm{CT}}^{(\mathrm{spec})}$ (∼0.5 ± 0.1) in U/LIRGs is a likely cause of a unique structure of buried AGNs, whose amount of material may be maintained through merger-induced supply from their host galaxies.

Sub/millimeter galaxies are a key population for the study of galaxy evolution because the majority of star formation at high redshifts occurred in galaxies deeply embedded in dust. To search for this population, we have performed an extensive survey with Atacama Large Millimeter/submillimeter Array (ALMA), called the ALMA Lensing Cluster Survey (ALCS). This survey covers 133 arcmin ^2 area and securely detects 180 sources at z ∼ 0.5–6 with a flux limit of ∼0.2 mJy at 1.2 mm. Here, we report the results of multiwavelength spectral energy distribution analysis of the whole ALCS sample, utilizing the observed-frame UV to millimeter photometry. We find that the majority of the ALCS sources lie on the star-forming main sequence, with a smaller fraction showing intense starburst activities. The ALCS sample contains high infrared-excess sources ( $\mathrm{IRX}=\mathrm{log}({L}_{\mathrm{dust}}/{L}_{\mathrm{UV}})\gt 1$ ), including two extremely dust-obscured galaxies (IRX > 5). We also confirm that the ALCS sample probes a broader range in lower dust mass than conventional submillimeter galaxy samples in the same redshift range. We identify six heavily obscured active galactic nucleus (AGN) candidates that are not detected in the archival Chandra data in addition to the three X-ray AGNs reported by Uematsu et al. (2023). The inferred AGN luminosity density shows a possible excess at z = 2–3 compared with that determined from X-ray surveys below 10 keV.

We investigate the black hole mass function (BHMF) and Eddington-ratio distribution function (ERDF) of broad-line active galactic nuclei (AGNs) at z = 4, based on a sample of 52 quasars with i < 23.2 at 3.50 ≤ z ≤ 4.25 from the Hyper Suprime-Cam Subaru Strategic Program S16A-Wide2 data set, and 1462 quasars with i < 20.2 in the same redshift range from the Sloan Digital Sky Survey data release 7 quasar catalog. Virial black hole (BH) masses of quasars are estimated using the width of the C _IV 1549 Å line and the continuum luminosity at 1350 Å. To obtain the intrinsic broad-line AGN BHMF and ERDF, we correct for the incompleteness in the low-mass and/or low-Eddington-ratio ranges caused by the flux-limited selection. The resulting BHMF is constrained down to $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }\sim 7.5$ . In comparison with broad-line AGN BHMFs at z ∼ 2 in the literature, we find that the number density of massive SMBHs peaks at higher redshifts, consistent with the downsizing evolutionary scenario. Additionally, the resulting ERDF shows a negative dependence on BH mass, suggesting more massive SMBHs tend to accrete at lower-Eddington ratios at z = 4. With the derived intrinsic broad-line AGN BHMF, we also evaluate the active fraction of broad-line AGNs among the entire SMBH population at z = 4. The resulting active fraction may suggest a positive dependence on BH mass. Finally, we examine the time evolution of broad-line AGN BHMF between z = 4 and 6 through solving the continuity equation. The results suggest that the broad-line AGN BHMFs at z = 4–6 only show evolution in their normalization, but with no significant changes in their shape.

We perform a systematic, multiwavelength spectral energy distribution (SED) analysis of X-ray detected active galactic nuclei (AGNs) at z = 0.2–0.8 with Sloan Digital Sky Survey (SDSS) counterparts in the Stripe 82 region, consisting of 60 type 1 and 137 type 2 AGNs covering a 2–10 keV luminosity range of $41.6\lt \mathrm{log}\ {L}_{{\rm{x}}}\lt 44.7$ . The latest CIGALE code, where dusty polar components are included, is employed. To obtain reliable host and AGN parameters in type 1 AGNs, we utilize the image-decomposed optical SEDs of host galaxies by Li et al. based on the Subaru Hyper-Suprime Cam images. The mean ratio of black hole masses ( M _BH ) and stellar masses ( M _stellar ) of our X-ray detected type 1 AGN sample, $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\mathrm{stellar}})=-2.7\pm 0.5$ , is close to the local relation between BH and stellar masses as reported by Li et al. for SDSS quasars. This ratio is slightly lower than that found for more luminous ( $\mathrm{log}{L}_{\mathrm{bol}}\gt 45$ ) type 1 AGNs at z ∼ 1.5. This can be explained by the AGN luminosity dependence of $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\mathrm{stellar}})$ , which little evolves with redshift. We confirm the trend that the UV-to-X-ray slope ( α _OX ) or X-ray-to-bolometric correction factor ( κ _2–10 ) increases with AGN luminosity or Eddington ratio. We find that type 1 and type 2 AGNs with the same luminosity ranges share similar host stellar mass distributions, whereas type 2s tend to show smaller AGN luminosities than type 1s. This supports the luminosity-dependent (or Eddington-ratio-dependent) unified scheme.

In this study, we examine photoionization outflows during the late stages of galaxy mergers, with a specific focus on the relation between the observed velocity of outflowing gas and the apparent effects of dust extinction. We used the N -body/smoothed particle hydrodynamics code ASURA for galaxy merger simulations. These simulations concentrated on identical galaxy mergers featuring supermassive black holes of 10 ^8 M _⊙ and gas fractions of 30% and 10%. From the simulation data, we derived velocity and velocity dispersion diagrams for the active galactic nuclei (AGN)-driven ionized outflowing gas. Our findings show that high-velocity outflows with velocity dispersions of 500 km s ^−1 or greater can be observed in the late stages of galactic mergers. Particularly, in buried AGNs, both the luminosity-weighted outflow velocity and velocity dispersion increase owing to the apparent effects of dust extinction. Owing to these effects, velocity–velocity dispersion diagrams display a noticeable blue-shifted tilt in models with higher gas fractions. Crucially, this tilt is not influenced by the AGN luminosity but emerges from the observational impacts of dust extinction. Our results imply that the observed high-velocity [O iii ] λ 5007 outflow exceeding 1000 km s ^−1 in buried AGNs may be linked to the dust extinction that occurs during the late stages of gas-rich galaxy mergers.

Spatially compact objects with extremely red color in the rest-frame optical to near-infrared (0.4–1 μ m) and blue color in the rest-frame ultraviolet (UV; 0.2–0.4 μ m) have been discovered at 5 < z < 9 using the James Webb Space Telescope (JWST). These extremely red objects (JWST-EROs) exhibit spectral energy distributions (SEDs) that are difficult to explain using a single component of either star-forming galaxies or quasars, leading to two-component models in which the blue UV and extremely red optical are explained using less-dusty and dusty spectra of galaxies or quasars, respectively. Here, we report the remarkable similarity in SEDs between JWST-EROs and blue-excess dust-obscured galaxies (BluDOGs) identified at 2 < z < 3. BluDOGs are a population of active galactic nuclei (AGNs) with black hole masses of ∼10 ^8–9 M _⊙ , which are 1 order of magnitude larger than those in some JWST-EROs. The Eddington ratios of BluDOGs are 1 or higher, whereas those of JWST-EROs are in the range of 0.1–1. Therefore, JWST-EROs are less massive, less active, and more common counterparts in higher- z of BluDOGs in cosmic noon. Conversely, JWST-EROs have a significantly higher fraction of those with blue excess than DOGs. We present the average UV spectra of BluDOGs as a comparison to JWST-EROs and discuss a coherent evolutionary scenario for dusty AGN populations.

We present the quasar luminosity function (LF) at z = 7, measured with 35 spectroscopically confirmed quasars at 6.55 < z < 7.15. The sample of 22 quasars from the Subaru High- z Exploration of Low-Luminosity Quasars (SHELLQs) project, combined with 13 brighter quasars in the literature, covers an unprecedentedly wide range of rest-frame ultraviolet magnitudes over −28 < M _1450 < −23. We found that the binned LF flattens significantly toward the faint end populated by the SHELLQs quasars. A maximum likelihood fit to a double power-law model has a break magnitude ${M}_{1450}^{* }=-{25.60}_{-0.30}^{+0.40}$ , a characteristic density ${{\rm{\Phi }}}^{* }={1.35}_{-0.30}^{+0.47}$ Gpc ^−3 mag ^−1 , and a bright-end slope $\beta =-{3.34}_{-0.57}^{+0.49}$ , when the faint-end slope is fixed to α = −1.2 as observed at z ≤ 6. The overall LF shape remains remarkably similar from z = 4 to 7, while the amplitude decreases substantially toward higher redshifts, with a clear indication of an accelerating decline at z ≥ 6. The estimated ionizing photon density, 10 ^48.2±0.1 s ^−1 Mpc ^−3 , is less than 1% of the critical rate to keep the intergalactic medium ionized at z = 7, and thus indicates that quasars are not a major contributor to cosmic reionization.

This study examines the impact of cluster environments on galaxy properties using data from the Hyper Suprime-Cam Subaru Strategic Program and an optically selected CAMIRA cluster sample. Specifically, the study analyzes the fractions of quiescent and green valley galaxies with stellar masses above 10 ^8.6 M _⊙ at z ∼ 0.2 and 10 ^9.8 M _⊙ at z ∼ 1.1, investigating their trends in radius and density. The results indicate that a slow quenching mechanism is at work, as evidenced by a radially independent specific star formation rate reduction of 0.1 dex for star-forming galaxies in a cluster environment. The study also finds that slow quenching dominates fast quenching only for low-mass galaxies (

We present, for the first time, dark matter halo (DMH) mass measurement of quasars at z ∼ 6 based on a clustering analysis of 107 quasars. Spectroscopically identified quasars are homogeneously extracted from the Hyper Suprime-Cam Strategic Survey Program wide layer over 891 deg ^2 . We evaluate the clustering strength by three different autocorrelation functions: projected correlation function, angular correlation function, and redshift–space correlation function. The DMH mass of quasars at z ∼ 6 is evaluated as ${5.0}_{-4.0}^{+7.4}\times {10}^{12}\,{h}^{-1}{M}_{\odot }$ with the bias parameter b = 20.8 ± 8.7 by the projected correlation function. The other two estimators agree with these values; though, each uncertainty is large. The DMH mass of quasars is found to be nearly constant ∼10 ^12.5 h ^−1 M _⊙ throughout cosmic time, suggesting that there is a characteristic DMH mass where quasars are always activated. As a result, quasars appear in the most massive halos at z ∼ 6, but in less extreme halos thereafter. The DMH mass does not appear to exceed the upper limit of 10 ^13 h ^−1 M _⊙ , which suggests that most quasars reside in DMHs with ${M}_{\mathrm{halo}}\lt {10}^{13}{h}^{-1}{M}_{\odot }$ across most of the cosmic time. Our results supporting a significant increasing bias with redshift are consistent with the bias evolution model with inefficient active galactic nucleus feedback at z ∼ 6. The duty cycle ( f _duty ) is estimated as 0.019 ± 0.008 by assuming that DMHs in some mass interval can host a quasar. The average stellar mass is evaluated from stellar-to-halo mass ratio as ${M}_{* }={6.5}_{-5.2}^{+9.6}\times {10}^{10}\,{h}^{-1}{M}_{\odot }$ , which is found to be consistent with [C ii ] observational results.

We present Karl G. Jansky Very Large Array K -band (19 GHz) observations of the redshifted CO(1–0) line emission toward the radio galaxy TN J0924−2201 at z = 5.2, which is one of the most distant radio galaxies with CO detected. With an angular resolution of ∼2″, the CO(1–0) line emission is resolved into three clumps, within ±500 km s ^−1 relative to its redshift, which is determined by Ly α . We find that the clumps are located off-center and 12–33 kpc away from the center of the host galaxy, which has counterparts in the Hubble Space Telescope i band, Spitzer/IRAC, and the Atacama Large Millimeter/submillimeter Array (ALMA) band 6 (230 GHz; 1.3 mm). With the ALMA detection, we estimate the infrared luminosity L _IR and the star formation rate (SFR) of the host galaxy to be (9.3 ± 1.7) × 10 ^11 L _⊙ and 110 ± 20 M _⊙ yr ^−1 , respectively. We also derive the 3 σ upper limit of ${M}_{{{\rm{H}}}_{2}}\lt 1.3\times {10}^{10}$ M _⊙ at the host galaxy. The detected CO(1–0) line luminosities of the three clumps, $L{{\prime} }_{\mathrm{CO}(1-0)}$ = (3.2–4.7) × 10 ^10 K km s ^−1 pc ^2 , indicate the presence of three massive molecular gas reservoirs, with ${M}_{{{\rm{H}}}_{2}}$ = (2.5–3.7) × 10 ^10 M _⊙ , assuming a CO-to-H _2 conversion factor of α _CO = 0.8 ${M}_{\odot }{({\rm{K}}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{pc}}^{2})}^{-1}$ , although the SFR is not elevated due to the nondetection of the ALMA 1.3 mm continuum (SFR < 40 M _⊙ yr ^−1 ). From the host galaxy, the nearest molecular gas clump, labeled “clump A,” is apparently in alignment with the radio jet axis, showing radio–CO alignment. The origins of these three clumps around TN J0924–2201 can possibly be interpreted as outflows, mergers, or jet-induced metal enrichment.

We investigate the variation in the mid-infrared spectral energy distributions of 373 low-redshift ( z < 0.4) star-forming galaxies, which reflects a variety of polycyclic aromatic hydrocarbon (PAH) emission features. The relative strength of PAH emission is parameterized as q _PAH , which is defined as the mass fraction of PAH particles in the total dust mass. With the aid of continuous mid-infrared photometric data points covering 7–24 μ m and far-infrared flux densities, q _PAH values are derived through spectral energy distribution fitting. The correlation between q _PAH and other physical properties of galaxies, i.e., gas-phase metallicity ( $12+\mathrm{log}({\rm{O}}/{\rm{H}})$ ), stellar mass, and specific star-formation rate (sSFR) are explored. As in previous studies, q _PAH values of galaxies with high metallicity are found to be higher than those with low metallicity. The strength of PAH emission is also positively correlated with the stellar mass and negatively correlated with the sSFR. The correlation between q _PAH and each parameter still exists even after the other two parameters are fixed. In addition to the PAH strength, the application of metallicity-dependent gas-to-dust mass ratio appears to work well to estimate gas mass that matches the observed relationship between molecular gas and physical parameters. The result obtained will be used to calibrate the observed PAH luminosity-total infrared luminosity relation, based on the variation of MIR-FIR SED, which is used in the estimation of hidden star formation.

We report the multiwavelength properties of millimeter galaxies hosting X-ray detected active galactic nuclei (AGNs) from the ALMA Lensing Cluster Survey (ALCS). ALCS is an extensive survey of well-studied lensing clusters with ALMA, covering an area of 133 arcmin ^2 over 33 clusters with a 1.2 mm flux-density limit of ∼60 μ Jy (1 σ ). Utilizing the archival data of Chandra, we identify three AGNs at z = 1.06, 2.09, and 2.84 among the 180 millimeter sources securely detected in the ALCS (of which 155 are inside the coverage of Chandra). The X-ray spectral analysis shows that two AGNs are not significantly absorbed ( $\mathrm{log}{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}\lt 23$ ), while the other shows signs of moderate absorption ( $\mathrm{log}{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}\sim 23.5$ ). We also perform spectral energy distribution modeling of X-ray to millimeter photometry. We find that our X-ray AGN sample shows both high mass-accretion rates (intrinsic 0.5–8 keV X-ray luminosities of ∼10 ^44–45 erg s ^−1 ) and star formation rates (≳100 M _⊙ yr ^−1 ). This demonstrates that a wide-area survey with ALMA and Chandra can selectively detect intense growth of both galaxies and supermassive black holes in the high-redshift universe.

The conditions under which galactic nuclear regions become active are largely unknown, although it has been hypothesized that secular processes related to galaxy morphology could play a significant role. We investigate this question using optical i -band images of 3096 SDSS quasars and galaxies at 0.3 < z < 0.6 from the Hyper Suprime-Cam Subaru Strategic Program, which possesses a unique combination of area, depth, and resolution, allowing the use of residual images, after removal of the quasar and smooth galaxy model, to investigate internal structural features. We employ a variational auto-encoder, which is a generative model that acts as a form of dimensionality reduction. We analyze the lower-dimensional latent space in search of features that correlate with nuclear activity. We find that the latent space does separate images based on the presence of nuclear activity, which appears to be associated with more pronounced components (i.e., arcs, rings, and bars) as compared to a matched control sample of inactive galaxies. These results suggest the importance of secular processes and possibly mergers (by their remnant features) in activating or sustaining black hole growth. Our study highlights the breadth of information available in ground-based imaging taken under optimal seeing conditions and having an accurate characterization of the point-spread function (PSF), thus demonstrating future science to come from the Rubin Observatory.

We conduct hard X-ray to radio multiwavelength spectral energy distribution (SED) decomposition for 57 local luminous and ultraluminous infrared galaxies observed with the Nuclear Spectroscopic Telescope Array and/or Swift/Burst Alert Telescope in the GOALS sample. We modify the latest SED-fitting code X-CIGALE by implementing the infrared (IR) CLUMPY model, allowing us to conduct the multiwavelength study with the X-ray torus model XCLUMPY self-consistently. Adopting the torus parameters obtained by the X-ray fitting, we estimate the properties of the host galaxies, active galactic nucleus (AGN) tori, and polar dust. The star formation rates (SFRs) become larger with merger stage and most of them are above the main sequence. The SFRs are correlated with radio luminosity, indicating starburst emission is dominant in the radio band. Although polar-dust extinction is much smaller than torus extinction, the UV-to-IR (mainly IR) polar dust luminosities are ∼2 times larger than the torus ones. The polar-dust temperature decreases while the physical size, estimated by the temperature and dust sublimation radius, increases with AGN luminosity from a few tens of parsec (early mergers) to kiloparsec scales (late mergers), where the polar dust likely comes from expanding (i.e., evolving) dusty outflows. A comparison between the SFRs and intrinsic AGN luminosities suggests that starbursts occur first and AGNs arise later, and overall their growth rates follow the simultaneous coevolution local galaxy–SMBH mass relation. We confirm the coexistence of intense starbursts, AGNs, and large-scale outflows in late mergers, supporting a standard AGN feedback scenario.