We present infrared K'- (2.1 micron) and L'-band (3.8 micron) high-spatial-resolution (<0.3") imaging observations of 17 nearby (z < 0.17) ultraluminous infrared galaxies (ULIRGs) assisted with the adaptive optics of the Subaru Telescope. We search for compact red K'-L' color emission as the indicator of luminous active galactic nuclei (AGNs) due to AGN-heated hot dust emission. Two luminous dual AGN candidates are revealed. Combining these results with those of our previous study, we can state that the detected fraction of luminous dual AGNs in nearby ULIRGs is much less than unity (<20%), even when infrared wavelengths >2 micron are used that should be sensitive to buried AGNs due to small dust extinction effects. For ULIRGs with resolved multiple nuclear K'-band emission, we estimate the activation of supermassive black holes (SMBHs) at individual galaxy nuclei in the form of AGN luminosity normalized by SMBH mass inferred from host galaxy stellar luminosity. We confirm a trend that more massive SMBHs in K'-band brighter primary galaxy nuclei are generally more active, with higher SMBH-mass-normalized AGN luminosity than less massive SMBHs in K'-band fainter secondary galaxy nuclei, as predicted by numerical simulations of gas-rich major galaxy mergers. In two sources, the presence of even infrared elusive extremely deeply buried AGNs is indicated by comparisons with available (sub)millimeter data. Non-synchronous SMBH activation (i.e., less activation of less massive SMBHs) and the possible presence of such infrared elusive AGNs may be responsible for the small fraction of infrared-detected luminous dual AGNs in nearby merging ULIRGs.
We report discovery of 41 new high-z quasars and luminous galaxies, which were spectroscopically identified at 5.7 < z < 6.9. This is the fourth in a series of papers from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, based on the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. We selected the photometric candidates by a Bayesian probabilistic algorithm, and then carried out follow-up spectroscopy with the Gran Telescopio Canarias and the Subaru Telescope. Combined with the sample presented in the previous pape…
We report the discovery of 28 quasars and 7 luminous galaxies at 5.7 $\le$ z $\le$ 7.0. This is the tenth in a series of papers from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which exploits the deep multi-band imaging data produced by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The total number of spectroscopically identified objects in SHELLQs has now grown to 93 high-z quasars, 31 high-z luminous galaxies, 16 [O III] emitters at z ~ 0.8, and 65 Galactic cool dwarfs (low-mass stars and brown dwarfs). These objects were found over 900 deg2, sur…
We present the results of our multifrequency observations for 10 ultraluminous infrared galaxies (ULIRGs) made by the Karl G. Jansky Very Large Array at 1.4, 5.5, 9.0, and 14.0 GHz. Our sample is selected from ULIRGs whose active galactic nuclei (AGNs) are not found at optical wavelengths ($\sim$70% of the entire ULIRGs), but whose presence is suggested by mid-infrared or submillimetre observations ($>50$% of the non-AGN ULIRGs at optical wavelengths). The statistical properties of the targets are similar to those of the entire ULIRG sample, which implies that ULIRGs have common radiative proc…
We present spectroscopic identification of 32 new quasars and luminous galaxies discovered at 5.7 < z < 6.8. This is the second in a series of papers presenting the results of the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which exploits the deep multi-band imaging data produced by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The photometric candidates were selected by a Bayesian probabilistic algorithm, and then observed with spectrographs on the Gran Telescopio Canarias and the Subaru Telescope. Combined with the sample presented in the previous pa…
We report the detection of the most luminous high-redshift Lyman Alpha Emitting galaxy (LAE) yet seen, with log L(Ly alpha) = 43.9 ergs/s. The galaxy -- COSMOS Lyman alpha 1, or COLA1 -- was detected in a search for ultra-luminous LAEs with Hyper Suprime-Cam on the Subaru telescope. It was confirmed to lie at z = 6.593 based on a Lyman alpha line detection obtained from followup spectroscopy with the DEIMOS spectrograph on Keck2. COLA1 is the first very high-redshift LAE to show a multi-component Lyman alpha line profile with a blue wing, which suggests that it could lie in a highly ionized re…
We present the photometric properties of a sample of infrared (IR) bright dust obscured galaxies (DOGs). Combining wide and deep optical images obtained with the Hyper Suprime-Cam (HSC) on the Subaru Telescope and all-sky mid-IR (MIR) images taken with Wide-Field Infrared Survey Explorer (WISE), we discovered 48 DOGs with $i - K_\mathrm{s} > 1.2$ and $i - [22] > 7.0$, where $i$, $K_\mathrm{s}$, and [22] represent AB magnitude in the $i$-band, $K_\mathrm{s}$-band, and 22 $μ$m, respectively, in the GAMA 14hr field ($\sim$ 9 deg$^2$). Among these objects, 31 ($\sim$ 65 %) show power-law spectral …
We study the UV luminosity functions (LFs) at $z\sim 4$, $5$, $6,$ and $7$ based on the deep large-area optical images taken by the Hyper Suprime-Cam (HSC) Subaru strategic program (SSP). On the 100 deg$^2$ sky of the HSC SSP data available to date, we make enormous samples consisting of a total of 579,565 dropout candidates at $z\sim 4-7$ by the standard color selection technique, 358 out of which are spectroscopically confirmed by our follow-up spectroscopy and other studies. We obtain UV LFs at $z \sim 4-7$ that span a very wide UV luminosity range of $\sim 0.002 - 100 \, L_{\rm UV}^\ast$ (…
Energetic nuclear outbursts have been discovered in luminous and ultraluminous infrared galaxies (U/LIRGs) at unexpectedly high rates. To investigate this population of transients, we performed a search in mid-IR data from the Wide-field Infrared Survey Explorer (WISE) satellite and its NEOWISE survey to detect and characterise luminous and smoothly evolving transients in a sample of 215 U/LIRGs. We report three new transients, all with $ΔL > 10^{43}$ erg s$^{-1}$, in addition to two previously known cases. Their host galaxies are all part of major galaxy mergers, and through radiative transfe…
We present the XMM-Newton X-ray analysis of 19 X-ray luminous galaxy clusters of low-to-mid redshift ($< 0.4$) selected from the MCXC cluster catalogue in the Hyper Supri%survey as the first work in our series paper. We derive the hydrostatic equilibrium mass and study scaling relations using i) the whole sample, ii) only relaxed clusters and iii) only disturbed clusters. When considering the whole sample, the $Y_{\rm X}$-$M_{\rm tot}$ and $M_{\rm gas}$-$M_{\rm tot}$ relations agree with self-similarity. In terms of morphology, relaxed clusters show a flatter relation in $L_{\rm X,ce}$-$M_{\rm…
We present the clustering analysis of photometric luminous red galaxies (LRGs) at a redshift range of $0.1\leq z \leq 1.05$ using $615,317$ photometric LRGs selected from the Hyper Suprime-Cam Subaru Strategic Program covering $\sim124$ deg$^{2}$. Our sample covers a broad range of stellar masses and photometric redshifts and enables a halo occupation distribution analysis to study the redshift and stellar-mass dependence of dark halo properties of LRGs. We find a tight correlation between the characteristic dark halo mass to host central LRGs, $M_{\min}$, and the number density of LRGs indepe…
We study properties of luminous X-ray pulsars using a simplified model of the accretion column. The maximal possible luminosity is calculated as a function of the neutron star (NS) magnetic field and spin period. It is shown that the luminosity can reach values of the order of $10^{40}\,{\rm erg/s}$ for the magnetar-like magnetic field ($B\gtrsim 10^{14}\,{\rm G}$) and long spin periods ($P\gtrsim 1.5\,{\rm s}$). The relative narrowness of an area of feasible NS parameters which are able to provide higher luminosities leads to the conclusion that $L\simeq 10^{40}\,\,{\rm erg/s}$ is a good esti…
A previously undetected X-ray source (L_X<10**36 erg/s) in the strongly star-forming galaxy M83 entered an ultraluminous state between August 2009 and December 2010. It was first seen with Chandra on 23 December 2010 at L_X ~ 4 10**39 ergs/s, and has remained ultraluminous through our most recent observations in December 2011, with typical flux variation of a factor of two. The spectrum is well fitted by a combination of absorbed power-law and disk black-body models. While the relative contributions of the models varies with time, we have seen no evidence for a canonical state transition. The …
We present the results of our ALMA observations of eleven (ultra)luminous infrared galaxies ((U)LIRGs) at J=4-3 of HCN, HCO+, 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 ULIRGs that contain or may contain luminous obscured 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, ou…
We present the results of ALMA $\sim$2 mm, $\lesssim$1$''$-resolution observations of ten (ultra)luminous infrared galaxies ([U]LIRGs; infrared luminosity $\gtrsim$ 10$^{11.7}$L$_{\odot}$) at $z <$ 0.15, targeting dense ($>$10$^{4}$ cm$^{-3}$) molecular (HCN, HCO$^{+}$, and HNC J=2-1) and 183 GHz H$_{2}$O 3$_{1,3}$-2$_{2,0}$ emission lines. Higher HCN to HCO$^{+}$ J=2-1 flux ratios are observed in some, but not all, AGN-important ULIRGs than in starburst-classified sources. We detect 183 GHz H$_{2}$O emission in almost all AGN-important ULIRGs, and elevated H$_{2}$O emission is found in two so…
I give a brief review of how X-rays from nearby galaxies are used as direct tracers of recent star formation. This leads to the conclusion that it is the most luminous point-like sources that are associated with star formation and that the majority of these are high-mass X-ray binaries.I then discuss a recent study that shows that ULXs are preferentially found in regions as young as or younger than typical HII regions in their host galaxies. Finally, I describe a new study that attempts to determine the maximum luminosity of ULXs in the local universe by searching for them in interacting galax…
We present our ALMA Cycle 4 measurements of the [CII] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity ($M_{\rm 1450} > -25$) quasars at $z \gtrsim 6$ discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [CII] line and FIR continuum luminosities lie in the ranges $L_{\rm [CII]} = (3.8-10.2) \times 10^8~L_\odot$ and $L_{\rm FIR} = (1.2-2.0) \times 10^{11}~L_\odot$, which are at least one order of magnitude smaller than those of optically-luminous quasars at $z \gtrsim 6$. We estimate the star formation rates (SFR) of our targets a…
We present the results of infrared K- (2.2 micron) and L'-band (3.8 micron) high-spatial-resolution (<0.2 arcsec) imaging observations of nearby gas- and dust-rich infrared luminous merging galaxies, assisted by the adaptive optics (AO) system on the Subaru 8.2-m telescope. We investigate the presence and frequency of red K-L' compact sources, which are sensitive indicators of active galactic nuclei (AGNs), including AGNs that are deeply buried in gas and dust. We observed 29 merging systems and confirmed at least one AGN in all but one system. However, luminous dual AGNs were detected in only…
We present the first discovery of dust-reddened quasars (red quasars) in the high-z universe (z >5.6). This is a result from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which is based on the sensitive multi-band optical imaging data produced by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. We identified four red quasar candidates from the spectroscopically confirmed 93 high-z quasars in the SHELLQs sample, based on detections in the Wide-field Infrared Survey Explorer (WISE) data at 3.4 and 4.6 um (rest-frame ~5000-6500 A). The amount of dust redde…
We examine the clustering of quasars over a wide luminosity range, by utilizing 901 quasars at $\overline{z}_{\rm phot}\sim3.8$ with $-24.73<M_{\rm 1450}<-22.23$ photometrically selected from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) S16A Wide2 date release and 342 more luminous quasars at $3.4<z_{\rm spec}<4.6$ having $-28.0<M_{\rm 1450}<-23.95$ from the Sloan Digital Sky Survey (SDSS) that fall in the HSC survey fields. We measure the bias factors of two quasar samples by evaluating the cross-correlation functions (CCFs) between the quasar samples and 25790 bright $z\sim4$ Lym…
Large-scale outflows are generally considered as a possible evidence that active galactic nuclei (AGNs) can severely affect their host galaxies. Recently an ultraluminous IR galaxy (ULIRG) at $z=0.49$, AKARI J0916248+073034, was found to have a galaxy-scale [OIII] $λ$5007 outflow with one of the highest energy-ejection rates at $z<1.6$. However, the central AGN activity estimated from its torus mid-IR (MIR) radiation is weak relative to the luminous [OIII] emission. In this work we report the first NuSTAR hard X-ray follow-up of this ULIRG to constrain its current AGN luminosity. The intrinsic…
The unique combination of superb spatial resolution, wide-area coverage, and deep depth of the optical imaging from the Hyper Suprime-Cam (HSC) Subaru Strategic Program is utilized to search for dual quasar candidates. Using an automated image analysis routine on 34,476 known SDSS quasars, we identify those with two (or more) distinct optical point sources in HSC images covering 796 deg^2. We find 421 candidates out to a redshift of 4.5 of which one hundred or so are more likely after filtering out contaminating stars. Angular separations of 0.6 - 4.0" correspond to projected separations of 3 …
We present a 2D study of the internal extinction on (sub)kiloparsec scales of a sample of local (z<0.1) (U)LIRGs, based on near-infrared Pa_a, Br_d, and Br_g line ratios, obtained with VLT-SINFONI integral-field spectroscopy. The 2D extinction (Av) distributions of the objects, map regions of ~3x3 kpc (LIRGs) and ~12x12 kpc (ULIRGs), with average angular resolutions (FWHM) of ~0.2 kpc and ~0.9 kpc, respectively. The individual Av galaxy distributions indicate a very clumpy dust structure already on sub-kiloparsec scales, with values (per spaxel) ranging from Av ~ 1 to 20 mag in LIRGs, and from…
This paper presents a detailed spectral pixel (spaxel) analysis of the ten Luminous Infrared Galaxies (LIRGs) previously observed with the Wide Field Spectrograph (WiFeS), an integral field spectrograph mounted on the ANU 2.3m telescope, and for which an abundance gradient analysis has already been presented by Rich et al. (2012). Here we use the strong emission line analysis techniques developed by Dopita et al. (2013) to measure the ionisation parameter and the oxygen abundance in each spaxel. In addition, we use the observed H$α$ flux to determine the surface rate of star formation ($M_{\od…
We study the comoving space density of X-ray-selected luminous active galactic nuclei (AGNs) and the obscured AGN fraction at high redshifts ($3 < z < 5$) in the Subaru/{\it XMM-Newton} Deep Survey (SXDS) field. From an X-ray source catalog with high completeness of optical identification thanks to deep optical images, we select a sample of 30 AGNs at $z > 3$ with intrinsic (de-absorbed and rest-frame 2--10 keV) luminosities of $L_{\rm X} = 10^{44-45}$ erg s$^{-1}$ detected in the 0.5--2 keV band, consisting of 20 and 10 objects with spectroscopic and photometric redshifts, respectively. Utili…
We report Chandra observations of the Scd galaxy NGC 2139, which is known to host a recently formed (10^7.6 yrs) nuclear star cluster. The star cluster is undetected in X-rays, with an upper bound on 0.5-7 keV luminosity of L_X < 7.1 x 10^37 erg/s. This bound implies a bolometric accretion luminosity <0.3 percent of the Eddington luminosity for a black hole with the mass (approximately 3400 M_sun) expected from extrapolation of the M-sigma relation. The lack of X-ray emission indicates that a black hole, if present, is not undergoing significant accretion at the current time. While the central…
We present the first results of our program to study a sample of local luminous infrared galaxies (LIRGs, L_IR = 10^11-10^12 L_sun) with the Spitzer infrared spectrograph (IRS). In these proceedings we investigate the behavior of the 9.7 um silicate feature in LIRGs. As opposed to the extreme silicate absorptions observed in ultraluminous infrared galaxies (ULIRGs, L_IR = 10^12-10^13 L_sun), LIRGs exhibit intermediate silicate absorption features, comparable to those of starburst galaxies. We also find that most of the LIRGs have the minima of the [NeIII]/[NeII] ratio located at their nuclei. …
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XXII. Chandra observations of narrow-line quasar candidates at z>6
Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB)（巴塞罗那大学宇宙科学研究所）；ICREA（加泰罗尼亚高级研究院）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（博洛尼亚天文物理与空间科学国家研究所）；Research Center for Space and Cosmic Evolution, Ehime University（爱媛大学宇宙演化研究中心）；Waseda Institute for Advanced Study (WIAS), Waseda University（早稻田大学高等研究院）；Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), UTIAS, Tokyo Institutes for Advanced Study, University of Tokyo（东京大学宇宙物质前沿研究联盟卡弗里宇宙起源与演化研究中心）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理学系）；Department of Astronomy, School of Science, The University of Tokyo（东京大学理学部天文学科）；Department of Physical Sciences, Ritsumeikan University（立命馆大学理工学部）；Academia Sinica Institute of Astronomy and Astrophysics（中央研究院天文及天文物理研究所）
We present the results of our ALMA HCN J=3-2 and HCO+ J=3-2 line observations of a uniformly selected sample (>25) of nearby ultraluminous infrared galaxies (ULIRGs) at z < 0.15. The emission of these dense molecular gas tracers and continuum are spatially resolved in the majority of observed ULIRGs for the first time with achieved synthesized beam sizes of ~0.2 arcsec or ~500 pc. In most ULIRGs, the HCN-to-HCO+ J=3-2 flux ratios in the nuclear regions within the beam size are systematically higher than those in the spatially extended regions. The elevated nuclear HCN J=3-2 emission could be r…
We present ALMA observations of the CO(1-0) line and 3-mm continuum emission in eight ultraluminous infrared (IR) quasi-stellar objects (QSOs) at z = 0.06-0.19. All eight IR QSO hosts are clearly resolved in their CO molecular gas emission with a median source size of 3.2 kpc, and seven out of eight sources are detected in 3-mm continuum, which is found to be more centrally concentrated with respect to molecular gas with sizes of 0.4-1.0 kpc. Our observations reveal a diversity of CO morphology and kinematics for the IR QSO systems which can be roughly classified into three categories, rotatin…
We present our ALMA multi-transition molecular line observational results for the ultraluminous infrared galaxy, IRAS 20551-4250, which is known to contain a luminous buried AGN and shows detectable vibrationally excited (v2=1f) HCN and HNC emission lines. The rotational J=1-0, 4-3, and 8-7 of HCN, HCO+, and HNC emission lines were clearly detected at a vibrational ground level (v=0). Vibrationally excited (v2=1f) J=4-3 emission lines were detected for HCN and HNC, but not for HCO+. Their observed flux ratios further support our previously obtained suggestion, based on J=3-2 data, that (1) inf…
Ultraluminous X-ray sources (ULXs) are thought to be powerful X-ray binaries (XRBs) and may contribute significantly to the redshift-dependent X-ray emission from star forming galaxies. We have assembled a uniform sample of 259 ULXs over the redshift range z=0.002-0.51 to constrain their physical nature and their contribution to the Cosmic X-Ray Background (CXB). The sample is constructed by crossmatching galaxies from the Sloan Digital Sky Survey with the Chandra Source Catalog and selecting off-nuclear X-ray sources after applying astrometric corrections. The fraction of contaminants is ~30%…
We present ALMA [CII] line and far-infrared (FIR) continuum observations of three $z > 6$ low-luminosity quasars ($M_{\rm 1450} > -25$) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [CII] line was detected in all three targets with luminosities of $(2.4 - 9.5) \times 10^8~L_\odot$, about one order of magnitude smaller than optically luminous ($M_{\rm 1450} \lesssim -25$) quasars. The FIR continuum luminosities range from $< 9 \times 10^{10}~L_\odot$ (3$σ$ limit) to $\sim 2 \times 10^{12}~L_\odot$, indicating a wide range in star formation rates in these galaxies. Most of the HSC…
Recent observations have suggested that the CIII]$\lambda1907/1909$ emission lines could be alternative diagnostic lines for galaxies in the reionization epoch. We use the F128N narrowband filter on the Hubble Space Telescope's ($\it{HST}$) Wide Field Camera 3 (WFC3) to search for CIII] emission in a sample of five galaxies at z = 5.7 in the Subaru Deep Field and the Subaru/XMM-Newton Deep Field. Using the F128N narrowband imaging, together with the broadband imaging, we do not detect CIII] emission for the five galaxies with $J_{\rm{AB}}$ ranging from 24.10 -- 27.00 in our sample. For the bri…
Chandra observations of the nearby, candidate Lyman-continuum (LyC) emitting galaxy Tol 0440-381 show brightening of an X-ray source by at least a factor of 4 to a luminosity of 1.6E40 erg/s over 3.8~days. The X-ray emission likely arises from either a low-luminosity AGN or an ultraluminous X-ray source. The properties of the X-ray source are similar to those found in Haro 11 and Tololo 1247-232, the only other LyC-emitting galaxies that have been resolved in X-rays. All three galaxies host luminous, variable, and hard spectrum X-ray sources that are likely accretion-powered. Accretion onto co…
We report the detection of molecular CO(1-0) gas in F00183-7111, one of the most extreme Ultra-Luminous Infrared Galaxies known, with the Australia Telescope Compact Array. We measure a redshift of 0.3292 for F00183-7111 from the CO(1-0) line and estimate the mass of the molecular gas in 00183 to be 1 $\times$ 10$^{10}$ M$_{\odot}$. We find that F00183-7111 is predominately powered by the AGN and only $\sim$14 per cent of the total luminosity is contributed by star-formation (SFR $\sim$220 M$_{\odot}$ yr$^{-1}$). We also present an optical image of F00183-7111, which shows an extension to the …
Cosmic rays (CRs) in starburst galaxies produce high energy gamma-rays by colliding with the dense interstellar medium (ISM). Arp 220 is the nearest ultra luminous infrared galaxy (ULIRG) that has star-formation at extreme levels, so it has long been predicted to emit high-energy gamma-rays. However, no evidence of gamma-ray emission was found despite intense efforts of search. Here we report the discovery of high-energy gamma-ray emission above 200 MeV from Arp 220 at a confidence level of $\sim 6.3 σ$ using 7.5 years of \textsl {Fermi} Large Area Telescope observations. The gamma-ray emissio…
We present Keck spectroscopic observations of three probable high redshift superluminous supernovae (SLSNe) from the Subaru HIgh-Z sUpernova CAmpaign (SHIZUCA), confirming redshifts of 1.851, 1.965 and 2.399. The host galaxies were selected for transient monitoring from multi-band photometric redshifts. The supernovae are detected during their rise, and the classically scheduled spectra are collected near maximum light. The restframe far-ultraviolet (FUV;$\sim$1000A-2500A) spectra include a significant host galaxy flux contribution and we compare our host galaxy subtracted spectra to UV-lumino…
The Chandra component of the Great Observatories All-Sky LIRG Survey (GOALS) presently contains 44 luminous and ultraluminous infrared galaxies with log (Lir/Lsun) = 11.73-12.57. Omitting 15 obvious AGNs, the other galaxies are, on average, underluminous in the 2-10 keV band by 0.7 dex at a given far-infrared luminosity, compared to nearby star-forming galaxies with lower star formation rates. The integrated spectrum of these hard X-ray quiet galaxies shows strong high-ionization Fe K emission (Fe XXV at 6.7 keV), which is incompatible with X-ray binaries as its origin. The X-ray quietness and…
