Search

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7, and at the Keck-I 10 m telescope using the Low-Resolution Imaging Spectrometer (LRIS) with slitmasks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure of relative flux calibration impractical. We demonstrate that spatially-resolved data from the IFS can be effectively used to correct the slit-mask spectral light curves. While we obtained no reliable lag owing to the lack of strong variability pattern in the light curves, we constrain the broad line time lag to be less than 3 hr, consistent with the photometric lag of $\sim80$ min reported by Woo et al. (2019). By exploiting the high-quality spectra, we measure the second moment of the broad component of the H$\alpha$ emission line to be $586\pm19$ km s$^{-1}$, superseding the lower value reported by Woo et al. (2019). Combining the revised line dispersion and the photometric time lag, we update the black hole mass as $(1.7\pm 0.3)\times10^4$ M$_{\odot}$., Comment: Accepted for publication in ApJ (Aug. 16th, 2021). 13 pages, 11 figures

We present initial results from a Hubble Space Telescope snapshot imaging survey of the host galaxies of Swift-BAT active galactic nuclei (AGN) at z, Accepted for publication in ApJS

We perform a deep wide-field imaging survey of nearby galaxies using H$\alpha$ and broadband filters to investigate the characteristics of star formation in galaxies. Motivated by the finding that star formation rates (SFRs) derived from H$\alpha$ fluxes in dwarf galaxies are systematically lower than those inferred from far-ultraviolet (FUV) fluxes, we attempt to determine whether the same trend exists in the extended disks of two star-forming galaxies. We perform spatially resolved photometry using grid-shaped apertures to measure the FUV and H$\alpha$ fluxes of star-forming regions. We also perform spectral energy distribution (SED) fittings using 11 photometric data (FUV-to-MIR) including data from the literature to estimate the local properties such as internal attenuation of individual star-forming clumps. Comparing SFR$_\mathrm{FUV}$ and SFR$_\mathrm{H\alpha}$, which are converted from the H$\alpha$ and FUV fluxes corrected for the local properties, we find that SFR$_\mathrm{H\alpha}$/SFR$_\mathrm{FUV}$ tends to decrease as the SFR decreases. We evaluate possible causes of this discrepancy between the two SFRs by restricting parameters in the SED fitting and conclude that deficient H$\alpha$ fluxes in the extended disks of galaxies are tightly correlated with recent starbursts. The strong and short starburst which is being rapidly suppressed over the last 10 Myr seems to induce a significant discrepancy between the SFR$_\mathrm{H\alpha}$ and SFR$_\mathrm{FUV}$. In addition, the recent bursts in the extended disks of galaxies appear to have occurred azimuth-symmetrically, implying that these were likely triggered by gas accretion or internal processes rather than external perturbation., Comment: 17 pages, 13 figures, Accepted for publication in ApJ

The FeII/MgII line flux ratio has been used as an indicator of the Fe/Mg abundance ratio in the broad line region (BLR) of active galactic nuclei (AGNs). On the basis of archival rest-frame UV spectra obtained via the Hubble Space Telescope and the Sloan Digital Sky Survey, we investigate the FeII/MgII ratios of type 1 AGNs at z < 2. Over wide dynamic ranges of AGN properties (i.e., black hole mass, AGN luminosity, and Eddington ratio), we confirm that the FeII/MgII ratio strongly correlates with Eddington ratio but not with black hole mass, AGN luminosity, or redshift. Our results suggest that the metallicity in the BLR are physically related to the accretion activity of AGNs, but not to the global properties of galaxies (i.e., galaxy mass and luminosity). With regard to the relation between the BLR metallicity and the accretion rate of AGNs, we discuss that metal cooling may play an important role in enhancing the gas inflow into the central region of host galaxies, resulting in the high accretion rate of AGNs., 14 pages, 9 figures, 4 tables, Accepted to Astrophysical Journal

The discovery of two-dimensional gapless Dirac fermions in graphene and topological insulators (TI) has sparked extensive ongoing research toward applications of their unique electronic properties. The gapless surface states in three-dimensional insulators indicate a distinct topological phase of matter with a non-trivial Z2 invariant that can be verified by angle-resolved photoemission spectroscopy or magnetoresistance quantum oscillation. In TI nanowires, the gapless surface states exhibit Aharonov-Bohm (AB) oscillations in conductance, with this quantum interference effect accompanying a change in the number of transverse one-dimensional modes in transport. Thus, while the density of states (DOS) of such nanowires is expected to show such AB oscillation, this effect has yet to be observed. Here, we adopt nanomechanical measurements that reveal AB oscillations in the DOS of a topological insulator. The TI nanowire under study is an electromechanical resonator embedded in an electrical circuit, and quantum capacitance effects from DOS oscillation modulate the circuit capacitance thereby altering the spring constant to generate mechanical resonant frequency shifts. Detection of the quantum capacitance effects from surface-state DOS is facilitated by the small effective capacitances and high quality factors of nanomechanical resonators, and as such the present technique could be extended to study diverse quantum materials at nanoscale., 15+16 pages, 4+11 figures

We examine the ultraviolet and optical colours of 906 cluster galaxies from the KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC). Galaxies have been divided into two categories, morphologically-disturbed and undisturbed galaxies, based on the visual signatures related to recent mergers. We find that galaxies with signatures of recent mergers show significantly bluer colours than undisturbed galaxies. Disturbed galaxies populate more on the cluster outskirts, suggesting recent accretion into the cluster environment, which implies that disturbed galaxies can be less influenced by the environmental quenching process and remain blue. However, we still detect bluer colours of disturbed galaxies in all locations (cluster core and outskirts) for the fixed morphology, which is difficult to understand just considering the difference in time since infall into a cluster. Moreover, blue disturbed galaxies show features seemingly related to recent star formation. Therefore, we suspect that mergers make disturbed galaxies keep their blue colour longer than undisturbed galaxies under the effect of the environmental quenching through either merger-induced star formation or central gas concentration which is less vulnerable for gas stripping., Comment: 13 pages, 15 figures; Accepted for publication in MNRAS

For site-specific soil ecological risk assessments (SERAs), an integrated chemical, ecotoxicological, and ecological analysis needs to be performed. The SERA guidelines of international institutions and countries recommend that a SERA be initiated at the screening level to save time and social economic cost, however, they provide no unified test species for this screening level. This study performed SERAs for field soils and confirmed the importance of selecting bioassay test species that reflect the ecotoxicity of field soils at the screening level. To confirm test species that reflect the ecological risk of field soils, correlation analysis was performed on the results of each bioassay with the integrated ecotoxicological risk index (EtoxRI). Our results showed that soil algae, nematodes, and plants were the most representative species in soil assays, with high correlation coefficients with EtoxRI. The results imply the importance of selecting test species that represent ecological risk for the screening level of SERAs. Based on these findings, when using SERAs, species sensitivity, ecological relevance, and economic aspects should be considered when selecting the bioassay test species.

We study the clustering property and physical parameters of gzK-colour-selected star-forming galaxies (sgzKs) based on the Canada–France–Hawaii Telescope surveys over 0.55 deg2 in the AKARI North Ecliptic Pole-Deep Field. Two-point correlation functions for two magnitude-limited cases, Ks < 21.1 (N = 234) and Ks < 21.5 (N = 428), are estimated using a single power-law function with the fixed slope of 0.8. The bias factors of sgzKs with Ks < 21.1 and 21.5 are 5.79 ± 1.07 and 4.00 ± 0.67, respectively, representing that sgzKs with z ∼ 1.7 reside in dark matter haloes more massive than $10^{13} ~\rm M_{\odot }$. We find that haloes hosting sgzKs with Ks < 21.5 evolve into haloes that host local massive galaxies with ∼6 L*. This suggests that sgzKs with Ks < 21.5 are likely to be predecessors of local massive galaxies. The evolutionary track of bias factor for host haloes of the bright sgzKs is similar to that of the bright passive extremely red objects, implying a possible connection between the two populations of galaxies. From the spectral energy distribution fitting, we estimate physical parameters and active galactic nucleus (AGN) contribution for 75 mid-infrared (MIR)-detected sgzKs with Ks < 21.5. The median values of stellar mass and star formation rate are 9.5 × 1010$\rm M_{\odot }$ and 162 $\rm M_{\odot }$ yr−1, respectively. MIR-detected sgzKs have a variety of AGN contributions ranging from 0 to 80 per cent. The number ratio of sgzKs with larger AGN contribution than 10 per cent is 30 per cent.

We report velocity-delay maps for prominent broad emission lines, Ly_alpha, CIV, HeII and H_beta, in the spectrum of NGC5548. The emission-line responses inhabit the interior of a virial envelope. The velocity-delay maps reveal stratified ionization structure. The HeII response inside 5-10 light-days has a broad single-peaked velocity profile. The Ly_alpha, CIV, and H_beta responses peak inside 10 light-days, extend outside 20 light-days, and exhibit a velocity profile with two peaks separated by 5000 km/s in the 10 to 20 light-day delay range. The velocity-delay maps show that the M-shaped lag vs velocity structure found in previous cross-correlation analysis is the signature of a Keplerian disk with a well-defined outer edge at R=20 light-days. The outer wings of the M arise from the virial envelope, and the U-shaped interior of the M is the lower half of an ellipse in the velocity-delay plane. The far-side response is weaker than that from the near side, so that we see clearly the lower half, but only faintly the upper half, of the velocity--delay ellipse. The delay tau=(R/c)(1-sin(i))=5 light-days at line center is from the near edge of the inclined ring, giving the inclination i=45 deg. A black hole mass of M=7x10^7 Msun is consistent with the velocity-delay structure. A barber-pole pattern with stripes moving from red to blue across the CIV and possibly Ly_alpha line profiles suggests the presence of azimuthal structure rotating around the far side of the broad-line region and may be the signature of precession or orbital motion of structures in the inner disk. Further HST observations of NGC 5548 over a multi-year timespan but with a cadence of perhaps 10 days rather than 1 day could help to clarify the nature of this new AGN phenomenon., 19 pages, 9 figures, ApJ in press

We present near-IR photometry and spectroscopy of 30 extremely luminous radio and mid-IR selected galaxies. With bolometric luminosities exceeding $\sim10^{13}$ $\rm{L_{\odot}}$ and redshifts ranging from $z = 0.880-2.853$, we use VLT instruments X-shooter and ISAAC to investigate this unique population of galaxies. Broad multi-component emission lines are detected in 18 galaxies and we measure the near-IR lines $\rm{H\rm{\beta}}$, $\text{[OIII]}\rm{\lambda}\rm{\lambda}4959,5007$ and $\rm{H\rm{\alpha}}$ in six, 15 and 13 galaxies respectively, with 10 $\rm{Ly\alpha}$ and five CIV lines additionally detected in the UVB arm. We use the broad $\text{[OIII]}\rm{\lambda}5007$ emission lines as a proxy for the bolometric AGN luminosity, and derive lower limits to supermassive black hole masses of $10^{7.9}$-$10^{9.4}$ $\text{M}_{\odot}$ with expectations of corresponding host masses of $10^{10.4}$-$10^{12.0}$ $\text{M}_{\odot}$. We measure $\rm{\lambda}_{Edd}$ > 1 for eight of these sources at a $2\sigma$ significance. Near-IR photometry and SED fitting are used to compare stellar masses directly. We detect both Balmer lines in five galaxies and use these to infer a mean visual extinction of $A_{V}$ = 2.68 mag. Due to non-detections and uncertainties in our $\rm{H\rm{\beta}}$ emission line measurements, we simulate a broad $\rm{H\rm{\beta}}$ line of FWHM = 1480 $\rm{kms^{-1}}$ to estimate extinction for all sources with measured $\rm{H\rm{\alpha}}$ emission. We then use this to infer a mean $A_{V}=3.62$ mag, demonstrating the highly-obscured nature of these galaxies, with the consequence of increasing our estimates of black-hole masses by an 0.5 orders of magnitude in the most extreme and obscured cases., Comment: Accepted for publication in MNRAS. 14 pages (+8 page appendix), 11 figures and 9 tables

We present rest-frame $B$ and $I$ imaging of 35 low-redshift ($z < 0.5$) Palomar-Green quasars using the Hubble Space Telescope Wide Field Camera 3. We perform multi-component two-dimensional image decomposition to separate the host galaxy from its bright active nucleus, characterize its morphology, and measure its photometric properties. Special care is devoted to quantifying the structural parameters of the galaxy bulge, determine its $B-I$ color, and estimate its stellar mass. Roughly half of the sample, comprising the less luminous ($L_{5100} \lesssim 10^{45}\,\mathrm{erg\,s^{-1}}$) but most high Eddington ratio quasars, reside in disk galaxies that are often barred and possess pseudo bulges. The large stellar masses, large effective radii, and faint surface brightnesses suggest that the host galaxies of the most luminous quasars are mostly ellipticals. Major mergers constitute only a minority ($\lesssim 20\%$) of our sample. Our quasar sample roughly obeys the scaling relations between black hole mass and host galaxy (bulge, core, total) stellar mass. Hosts with black holes more massive than $\sim 10^8\,M_\odot$ behave similarly to classical bulges and early-type galaxies, while those with less massive black holes, particular the narrow-line Seyfert 1s, are consistent with pseudo bulges in late-type galaxies. The host galaxy bulges, irrespective of whether they are classical or pseudo, follow the relatively tight inverse relation between effective radius and mean effective surface brightness of inactive classical bulges and ellipticals. We argue that pseudo bulges experience recent or ongoing nuclear star formation., 24 pages, 12 figure, 3 tables, accepted for publication in ApJ

We have performed a spectral decomposition to search for dual active galactic nuclei (DAGNs) in the Sloan Digital Sky Survey (SDSS) quasars with $z, Ap.J. in press

We present an 850-μm mosaic map and extracted catalogue of submillimetre sources in the extended North Ecliptic Pole (NEP) region over about 2 deg2. The 850-μm map is constructed using newly obtained observations by SCUBA-2 at the East Asian Observatory’s James Clerk Maxwell Telescope, carried out using the observatory’s large programme opportunities. The recent 850-μm survey has extended the submillimetre data coverage by almost a factor of 4 compared to previous surveys, with a depth of σrms = 1.0–2.3 mJy beam−1. The catalogue contains 549 sources selected above a significance level of 4σ, where the false-detection rate is 10 per cent; a higher threshold of 4.5σ is required in order to achieve a false-detection rate below 3 per cent, which results in 342 sources being selected. Despite the large spatial variation of the noise, the deboosted flux density of sources is comparable to results from the SCUBA-2 Cosmology Legacy Survey (S2CLS), which covered the central 0.6 deg2 of our survey area with better sensitivity. We construct the source counts at 850 μm, finding results in agreement with other 850-μm surveys in cosmological blank fields over S850 = 4–15 mJy. We find a slight excess of bright galaxies (S850 > 15 mJy), which can be considered to be at ɀphot = 2–4. The 850-μm data adds valuable long-wavelength information to mid-infrared-selected sources from the AKARI NEP-deep and NEP-wide surveys, which will be helpful in preparing for future near-infrared to millimetre wavelength observations in the NEP region. Our 850-μm mosaic map and source catalogue will be made publicly available.

We present geometric and dynamical modeling of the broad line region for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The dataset includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H$\beta$, C IV, and Ly$\alpha$ broad emission lines. We find an extended disk-like H$\beta$ BLR with a mixture of near-circular and outflowing gas trajectories, while the C IV and Ly$\alpha$ BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C IV and Ly$\alpha$ emission arising at smaller radii than the H$\beta$ emission. Using the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of $\log_{10}(M_{\rm BH}/M_\odot) = 7.64^{+0.21}_{-0.18}$. We examine the effect of using the $V$ band instead of the UV continuum light curve on the results and find a size difference that is consistent with the measured UV-optical time lag, but the other structural and kinematic parameters remain unchanged, suggesting that the $V$ band is a suitable proxy for the ionizing continuum when exploring the BLR structure and kinematics. Finally, we compare the H$\beta$ results to similar models of data obtained in 2008 when the AGN was at a lower luminosity state. We find that the size of the emitting region increased during this time period, but the geometry and black hole mass remain unchanged, which confirms that the BLR kinematics suitably gauge the gravitational field of the central black hole., Comment: 26 pages, 19 figures, 1 table, accepted for publication in ApJ

On Earth near sunset, the sun may cast "crepuscular rays" such that clouds near the horizon obscure the origin of light scattered in bright rays. In principle, AGN should be able to produce similar effects. Using new Hubble Space Telescope (HST) near-infrared and optical observations, we show that the active galaxy IC 5063 contains broad radial rays extending to $\gtrsim$11 kpc from the nucleus. We argue that the bright rays may arise from dusty scattering of continuum emission from the active nucleus, while the dark rays are due to shadowing near the nucleus, possibly by a warped torus. We also consider alternative AGN-related and stellar origins for the extended light., Accepted for publication to ApJ Letters. 13 pages, 5 figures. Facilitated by Twitter discussion (see https://twitter.com/SpaceGeck/status/1201350966945017856). This version corrects figure labels and includes other more minor updates

We report on observations of redshifted CO(1-0) line emission and observed-frame $\rm\sim$ 30GHz radio continuum emission from five ultra-luminous, mid-IR selected hot, Dust-Obscured Galaxies (Hot DOGs) at $z\rm\gtrsim$ 3 using the Karl G. Jansky Very Large Array. We detect CO(1-0) line emission in all five Hot DOGs, with one of them at high signal to noise. We analyse FIR-radio spectral energy distributions, including dust, free-free and synchrotron emission for the galaxies. We find that most of the 115 GHz rest-frame continuum is mostly due to synchrotron or free-free emission, with only a potentially small contribution from thermal emission. We see a deficit in the rest-frame 115 GHz continuum emission compared to dusty star-forming galaxies (DSFGs) and sub-millimetre galaxies (SMGs) at high redshift, suggesting that Hot DOGs do not have similar cold gas reserves compared with star-forming galaxies. One target, W2305-0039, is detected in the FIRST 1.4 GHz survey, and is likely to possess compact radio jets. We compare to the FIR-radio correlation, and find that at least half of the Hot DOGs in our sample are radio-quiet with respect to normal galaxies. These findings suggest that Hot DOGs have comparably less cold molecular gas than star-forming galaxies at lower, $z\rm\sim$ 2 redshifts, and are dominated by powerful, yet radio-quiet AGN., 15 pages, 12 figures, accepted for publication in MNRAS

Faint $z\sim5$ quasars with $M_{1450}\sim-23$ mag are known to be the potentially important contributors to the ultraviolet ionizing background in the post-reionization era. However, their number density has not been well determined, making it difficult to assess their role in the early ionization of the intergalactic medium (IGM). In this work, we present the updated results of our $z\sim5$ quasar survey using the Infrared Medium-deep Survey (IMS), a near-infrared imaging survey covering an area of 85 deg$^{2}$. From our spectroscopic observations with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8 m Telescope, we discovered eight new quasars at $z\sim5$ with $-26.1\leq M_{1450} \leq -23.3$. Combining our IMS faint quasars ($M_{1450}>-27$ mag) with the brighter Sloan Digital Sky Survey (SDSS) quasars ($M_{1450}, Comment: 21 pages, 14 figures, 7 tables. Accepted for publication in ApJ

An ultraluminous X-ray source (ULX) in NGC 5252 has been known as a strong candidate for an off-nuclear intermediate-mass black hole. We present near-infrared imaging data of the ULX obtained with the William Herschel Telescope. Using this data we estimate a stellar mass associated with the ULX of $\approx 10^{7.9\pm0.1}M_{\rm \odot}$ , suggesting that it could be (the remnant of) a dwarf galaxy that is in the process of merging with NGC 5252. Based on a correlation between the mass of the central black hole (BH) and host galaxy, the ULX is powered by a $10^5M_{\rm \odot}$ black hole. Alternatively, if the BH mass is $\approx 10^6M_{\rm \odot}$ or larger, the host galaxy of the ULX must have been heavily stripped during the merger. The ULX $K_s$-band luminosity is two orders of magnitude smaller than that expected from an ordinary active galactic nucleus with the observed [O III] luminosity, which also suggests the ULX lacks a dusty torus. We discuss how these findings provide suggestive evidence that the ULX is hosting an intermediate-mass black hole., Comment: To appear in MNRAS

We present newly discovered dwarf galaxy candidates in deep and wide-field images of NGC 1291 obtained with the Korea Microlensing Telescope Network. We identify 15 dwarf galaxy candidates by visual inspection. Using imaging simulations, we demonstrate that the completeness rate of our detection is greater than 70% for the central surface brightness value of ${\mu}_{0,R}\lesssim26$ mag arcsec$^{-2}$ and for magnitudes $M_R\lesssim-10$ mag. The structural and photometric properties of the dwarf galaxy candidates appear to be broadly consistent with those of ordinary dwarf galaxies in nearby groups and clusters, with ${\mu}_{0,R}\sim$ 22.5 to 26.5 mag arcsec$^{-2}$ and effective radii of 200 pc to 1 kpc. The dwarf galaxy candidates show a concentration towards NGC 1291 and tend to be redder the closer they are to the center, possibly indicating that they are associated with NGC 1291. The dwarf candidates presented in this paper appear to be bluer than those in denser environments, revealing that the quenching of star formation in dwarf galaxies is susceptible to the environment, while the morphology shaping is not., Comment: 19 pages; 9 figures, 2 tables; Accepted for publication in ApJ

We have observed the environments of a population of 33 heavily dust obscured, ultra-luminous, high-redshift galaxies, selected using WISE and NVSS at $z>$1.3 with the Infra-Red Array Camera on the $Spitzer$ Space Telescope over $\rm5.12\,'\times5.12\,'$ fields. Colour selections are used to quantify any potential overdensities of companion galaxies in these fields. We find no significant excess of galaxies with the standard colour selection for IRAC colours of $\rm[3.6]-[4.5]>-0.1$ consistent with galaxies at $z>$1.3 across the whole fields with respect to wide-area $Spitzer$ comparison fields, but there is a $\rm>2��$ statistical excess within $\rm0.25\,'$ of the central radio-WISE galaxy. Using a colour selection of $\rm[3.6]-[4.5]>0.4$, 0.5 magnitudes redder than the standard method of selecting galaxies at $z>$1.3, we find a significant overdensity, in which $\rm76\%$ ($\rm33\%$) of the 33 fields have a surface density greater than the $\rm3��$ ($\rm5��$) level. There is a statistical excess of these redder galaxies within $\rm0.5\,'$, rising to a central peak $\rm\sim2$--4 times the average density. This implies that these galaxies are statistically linked to the radio-WISE selected galaxy, indicating similar structures to those traced by red galaxies around radio-loud AGN., 17 pages, 16 figures, 2 tables

We model the ultraviolet spectra of the Seyfert 1 galaxy NGC~5548 obtained with the Hubble Space Telescope during the 6-month reverberation-mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Ly$\alpha$ and C IV, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. The velocity-binned lag profiles of Ly$\alpha$ and C IV have a double-peaked structure indicative of a truncated Keplerian disk. The narrow absorption lines show delayed response to continuum variations corresponding to recombination in gas with a density of $\sim 10^5~\rm cm^{-3}$. The high-ionization narrow absorption lines decorrelate from continuum variations during the same period as the broad emission lines. Analyzing the response of these absorption lines during this period shows that the ionizing flux is diminished in strength relative to the far-ultraviolet continuum. The broad absorption lines associated with the X-ray obscurer decrease in strength during this same time interval. The appearance of X-ray obscuration in $\sim\,2012$ corresponds with an increase in the luminosity of NGC 5548 following an extended low state. We suggest that the obscurer is a disk wind triggered by the brightening of NGC 5548 following the decrease in size of the broad-line region during the preceding low-luminosity state., Comment: 50 pages, 30 figures, uses aastex62.cls. Accepted for publication in ApJ, 07/06/2019. High-level products page in MAST will go live after 7/15/2019. Replaced Figure 4 on 7/12/2019 to be more red/green color-blind friendly

We study the clustering property of extremely red objects (EROs) using Canada–France–Hawaii Telescope (CFHT) surveys with 0.55 deg2 in the AKARI north ecliptic pole (NEP) deep field. EROs are selected by the color criterion of r′ − Ks > 3.66, which is equivalent to (R − Ks)Vega > 5. We conducted the clustering analysis for two magnitude-limited cases, Ks < 20.3 (N = 363) and Ks < 20.9 (N = 727), using two-point angular correlation represented by a single power-law function. By fixing a power-law (with 0.8), the correlation lengths of EROs with Ks < 20.3 and Ks < 20.9 are 9.10 ± 1.86 and 7.81 ± 1.21 h−1 Mpc, respectively. We find that bias factors of EROs with Ks < 20.3 and Ks < 20.9 are 3.19 ± 0.59 and 2.83 ± 0.40, respectively, revealing that EROs reside in dark matter halos heavier than $\sim 10^{13}\, M_{\odot }$. To investigate possible descendants of EROs with Ks < 20.9, we calculate how the bias for dark matter halos that host EROs evolves by accounting for mass growth of halos along the redshift. We find that halos hosting EROs evolve into halos hosting local massive galaxies with 2–$7\, L^{*}$. It suggests that passive EROs with Ks < 20.9 are likely to be progenitors of massive galaxies in the present universe. The comparison between passive EROs (pEROs) and star-forming EROs (sEROs) classified by near-infrared colors shows that pEROs seem to be connected with more massive local galaxies. By fitting spectral energy distributions (SEDs), we estimate active galactic nucleus (AGN) contribution for 68 sEROs which are selected in mid-IR bands. AGN contributions to the IR luminosity are less than $10\%$ except for six sEROs. At least in the IR-selected sEROs, the contribution of AGN seems to be not significant.

Black hole mass scaling relations suggest that extremely massive black holes (EMBHs) with $M_\mathrm{BH}\ge10^{9.4}\,M_{\odot}$ are found in the most massive galaxies with $M_\mathrm{star}\ge10^{11.6}\,M_{\odot}$, which are commonly found in dense environments, like galaxy clusters. Therefore, one can expect that there is a close connection between active EMBHs and dense environments. Here, we study the environments of 9461 galaxies and 2943 quasars at $0.24 \le z \le 0.40$, among which 52 are extremely massive quasars with $\log(M_\mathrm{BH}/M_{\odot}) \ge 9.4$, using Sloan Digital Sky Survey and MMT Hectospec data. We find that, on average, both massive quasars and massive galaxies reside in environments more than $\sim2$ times as dense as those of their less massive counterparts with $\log(M_\mathrm{BH}/M_{\odot}) \le 9.0$. However, massive quasars reside in environments about half as dense as inactive galaxies with $\log(M_\mathrm{BH}/M_{\odot}) \ge 9.4$, and only about one third of massive quasars are found in galaxy clusters, while about two thirds of massive galaxies reside in such clusters. This indicates that massive galaxies are a much better signpost for galaxy clusters than massive quasars. The prevalence of massive quasars in moderate to low density environments is puzzling, considering that several simulation results show that these quasars appear to prefer dense environments. Several possible reasons for this discrepancy are discussed, although further investigation is needed to obtain a definite explanation., 34 pages, 26 figures, 2 tables, accepted for publication in the ApJ

We developed a spectroscopic monitoring project to investigate the kinematics of the broad-line region (BLR) in active galactic nuclei (AGN) with ultra-fast outflows (UFOs). Mrk~79 is a radio-quiet AGN with UFOs and warm absorbers, had been monitored by three reverberation mapping (RM) campaigns, but its BLR kinematics is not understood yet. In this paper, we report the results from a new RM-campaign of Mrk~79, which was undertaken by Lijiang 2.4-m telescope. Mrk~79 is seeming to come out the faint state, the mean flux approximates a magnitude fainter than historical record. We successfully measured the lags of the broad emission lines including H$\beta~\lambda4861$, H$\gamma~\lambda4340$, He II $\lambda4686$ and He I $\lambda5876$ with respect to the varying AGN continuum. Based on the broad H$\beta~\lambda4861$ line, we measured black hole (BH) mass of $M_{\bullet}=5.13^{+1.57}_{-1.55}\times10^{7}M_{\odot}$, estimated accretion rates of ${\dot{M}_{\bullet}}=(0.05\pm0.02)~L_{\rm Edd}~c^{-2}$, indicating that Mrk~79 is a sub-Eddington accretor. We found that Mrk~79 deviates from the canonical Radius$-$Luminosity relationship. The marginal blueshift of the broad He II $\lambda4686$ line detected from rms spectrum indicates outflow of high-ionization gas. The velocity-resolved lag profiles of the broad H$\gamma~\lambda4340$, H$\beta~\lambda4861$, and He I $\lambda5876$ lines show similar signatures that the largest lag occurs in the red wing of the lines then the lag decreases to both sides. These signatures should suggest that the BLR of Keplerian motion probably exists the outflow gas motion. All findings including UFOs, warm absorbers, and the kinematics of high- and low-ionization BLR, may provide an indirect evidence that the BLR of Mrk~79 probably originates from disk wind., Comment: 21 pages, 16 figures, accepted for publication in ApJ

To understand the physical origin of the close connection between supermassive black holes and their host galaxies, it is vital to investigate star formation properties in active galaxies. Using a large dataset of nearby type 1 active galactic nuclei (AGNs) with detailed structural decomposition based on high-resolution optical images obtained with the Hubble Space Telescope, we study the correlation between black hole mass and bulge luminosity and the (Kormendy) relation between bulge effective radius and surface brightness. In both relations, the bulges of type 1 AGNs tend to be more luminous than those of inactive galaxies with the same black hole mass or the same bulge size. This suggests that the central regions of AGN host galaxies have characteristically lower mass-to-light ratios than inactive galaxies, most likely due to the presence of a younger stellar population in active systems. In addition, the degree of luminosity excess appears to be proportional to the accretion rate of the AGN, revealing a physical connection between stellar growth and black hole growth. Adopting a simple toy model for the increase of stellar mass and black hole mass, we show that the fraction of young stellar population flattens out toward high accretion rates, possibly reflecting the influence of AGN-driven feedback., Comment: To appear in ApJ

We present medium-resolution spectra ($R \sim 2000$--4000) at 0.4--1.0\,$\mu$m and 0.7--2.5\,$\mu$m of 16 active galactic nuclei (AGNs) selected with red color in the near-infrared (NIR) of $J - K > 2.0$ mag at $z \sim 0.3$. We fit the H$\beta$, H$\alpha$, P$\beta$, and P$\alpha$ lines from these spectra to obtain their luminosities and line widths. We derive the $E(B-V)$ color excess values of the NIR-red AGNs using two methods, one based on the line-luminosity ratios and another based on the continuum slopes. The two $E(B-V)$ values agree with each other at rms dispersion $\sim$ 0.249. About half of the NIR-red AGNs have $g'-K < 5$ magnitude, and we find that these NIR red, but blue in optical-NIR AGNs, have $E(B-V) \sim 0$, suggesting that a significant fraction of the NIR color-selected red AGNs are unobscured or only mildly obscured. After correcting for the dust extinction, we estimate the black hole (BH) masses and the bolometric luminosities of the NIR-red AGNs using the Paschen lines to calculate their Eddington ratios ($\lambda_{\rm Edd}$). The median Eddington ratios of nine NIR-red AGNs ($\log (\lambda_{\rm Edd}) \simeq -0.654 \pm 0.176$) are only mildly higher than those of unobscured type 1 AGNs ($\log (\lambda_{\rm Edd}) \simeq -0.961 \pm 0.008$). Moreover, we find that the $M_{\rm BH}$--$\sigma_{\ast}$ relation for three NIR-red AGNs is consistent with that of unobscured type 1 AGNs at similar redshift. These results suggest that the NIR red color selection alone is not effective at picking up dusty, intermediate-stage AGNs., Comment: 26 pages, 16 figures, 8 tables, Published in ApJS

JINGLE is a new JCMT legacy survey designed to systematically study the cold interstellar medium of galaxies in the local Universe. As part of the survey we perform 850um continuum measurements with SCUBA-2 for a representative sample of 193 Herschel-selected galaxies with M*>10^9Msun, as well as integrated CO(2-1) line fluxes with RxA3m for a subset of 90 of these galaxies. The sample is selected from fields covered by the Herschel-ATLAS survey that are also targeted by the MaNGA optical integral-field spectroscopic survey. The new JCMT observations combined with the multi-wavelength ancillary data will allow for the robust characterization of the properties of dust in the nearby Universe, and the benchmarking of scaling relations between dust, gas, and global galaxy properties. In this paper we give an overview of the survey objectives and details about the sample selection and JCMT observations, present a consistent 30 band UV-to-FIR photometric catalog with derived properties, and introduce the JINGLE Main Data Release (MDR). Science highlights include the non-linearity of the relation between 850um luminosity and CO line luminosity, and the serendipitous discovery of candidate z>6 galaxies., MNRAS in press, 25 pages

We present a spatially resolved analysis of ionized gas at the nuclear region of the nearby galaxy NGC 1068. While NGC 1068 has been known to have gas outflows driven by its active galactic nucleus (AGN), more complex kinematical signatures were recently reported, which were inconsistent with a rotation or simple biconical outflows. To account for the nature of gas kinematics, we performed a spatially resolved kinematical study, finding a morphologically symmetric pair of approaching and receding gas blobs in the northeast region. The midpoint of the two blobs is located at a distance of 180 pc from the nucleus in the projected plane. The ionized gas at the midpoint shows zero velocity and high velocity dispersion, which are characteristics of an outflow-launching position, as the two sides of a bicone, i.e., approaching and receding outflows are superposed on the line of sight, leading to no velocity shift but high velocity dispersion. We investigate the potential scenario of an additional AGN based on a multiwavelength data set. While there are other possibilities, i.e., X-ray binary or supernova shock, the results from optical spectropolarimetry analysis are consistent with the presence of an additional AGN, which likely originates from a minor merger., 12 pages, 7 figures, ApJ, in press

We address the impact of young radio jets on the ISM and star formation in a sample of radiatively efficient, highly obscured, radio AGN with look back times that place them near the peak of the galaxy and BH building era, z ∼ 1–3. By selecting systems with a high mid-infrared (MIR) luminosity we aim to identify radiatively efficient (“quasar-mode” or “radiative-mode”) AGN in a peak fueling phase, and by selecting compact radio sources we favor young or re-generated radio jets which are confined within the hosts. By selecting AGN which are very red through the optical-MIR we favor highly obscured systems likely to have been recently merger-triggered and still in the pre-blow-out phase of AGN feedback into the surrounding ISM. ALMA imaging at 345 GHz of 49 sources has revealed that they are accretion dominated, relative to star formation, with luminosities reaching 1014 L⊙. Extensive VLA imaging at 8–10 GHz in both A-array and B-array for 155 sources reveals that the majority of these powerful radio systems are compact on

Galaxy mergers are expected to produce multiple supermassive black holes (SMBHs) in close-separation, but the detection of such SMBHs has been difficult. 2MASS J165939.7$+$183436 is a red active galactic nucleus (AGN) that is a prospective merging SMBH candidate owing to its merging features in Hubble Space Telescope imaging and double-peaked broad emission lines (BELs). Herein, we report a Gemini Multi-Object Spectrograph Integral Field Unit observation of a double-peaked broad H$��$ line of 2MASS J165939.7$+$183436. Furthermore, we confirm the existence of two BEL peaks that are kinematically separated by 3000\,$\rm km\,s^{-1}$, with the SMBH of each BEL component weighing at $10^{8.92\pm0.06}\,M_{\rm \odot}$ and $10^{7.13\pm0.06}\,M_{\rm \odot}$, if they arise from independent BELs near the two SMBHs. The BEL components were not separated at $>0\farcs1$; however, under several plausible assumptions regarding the fitting of each spaxel, the two components are found to be spatially separated at $0\farcs085$ ($\sim250$\,pc). Different assumptions for the fitting can lead to a null ($< 0\farcs05$) or a larger spatial separation ($\sim0\farcs15$). Given the uncertainty regarding the spatial separation, various models, such as the disk emitter and multiple SMBH models, are viable solutions to explain the double BEL components. These results will promote future research for finding more multiple SMBH systems in red AGNs, and higher-resolution imaging validates these different models., 12 pages, 6 figures, 1 table, Published in ApJ

The faint quasars with $M_{1450}>-24$ mag are known to hold the key to the determination of the ultraviolet emissivity for the cosmic re-ionization. But only a few have been identified so far because of the limitations on the survey data. Here, we present the first results of the $z\sim5$ faint quasar survey with the Infrared Medium-deep Survey (IMS), which covers $\sim100$ deg$^{2}$ areas in $J$-band to the depths of $J_{\rm AB}\sim23$ mag. To improve selection methods, the medium-band follow-up imaging has been carried out using the SED camera for QUasars in Early uNiverse (SQUEAN) on the Otto Struve 2.1 m Telescope. The optical spectra of the candidates were obtained with 8-m class telescopes. We newly discovered 10 quasars with $-25, Comment: 24 pages, 9 figures, 6 tables. Accepted for publication in ApJ

SPHEREx, a mission in NASA’s Medium Explorer (MIDEX) program recently selected for Phase-A implementation, is an all-sky survey satellite that will produce a near-infrared spectrum for every 6 arcsecond pixel on the sky. SPHEREx has a simple, high-heritage design with large optical throughput to maximize spectral mapping speed. While the legacy data products will provide a rich archive of spectra for the entire astronomical community to mine, the instrument is optimized for three specific scientific goals: to probe inflation through the imprint primordial non-Gaussianity left on today’s large-scale cosmological structure; to survey the Galactic plane for water and other biogenic ices through absorption line studies; and to constrain the history of galaxy formation through power spectra of background fluctuations as measured in deep regions near the ecliptic poles. The aluminum telescope consists of a heavily baffled, wide-field off-axis reflective triplet design. The focal plane is imaged simultaneously by two mosaics of H2RG detector arrays separated by a dichroic beamsplitter. SPHEREx assembles spectra through the use of mass and volume efficient linear variable filters (LVFs) included in the focal plane assemblies, eliminating the need for any dispersive or moving elements. Instead, spectra are constructed through a series of small steps in the spacecraft attitude across the sky, modulating the location of an object within the FOV and varying the observation wavelength in each exposure. The spectra will cover the wavelength range between 0.75 and 5.0 µm at spectral resolutions ranging between R=35 and R=130. The entire telescope is cooled passively by a series of three V-groove radiators below 80K. An additional stage of radiative cooling is included to reduce the long wavelength focal plane temperature below 60K, controlling the dark current. As a whole, SPHEREx requires no new technologies and carries large technical and resource margins on every aspect of the design.

Korea Astronomy and Space Science Institute (KASI) successfully developed the Near-infrared Imaging Spectrometer for Star formation history (NISS), which is a scientific payload for the next-generation small satellite-1 (NEXTSat-1) in Korea and is expected to be launched in 2018. The major science cases of NISS are to probe the star formation in local and early Universe through the imaging spectroscopic observations in the near-infrared. The off-axis catadioptric optics with 150mm aperture diameter is designed to cover the FoV of 2x2 deg with the passband of 0.95-2.5μm. The linear variable filter (LVF) is adopted as a disperse element with spectral resolution of R~20. Given the error budgets from the optical tolerance analysis, all spherical and non-spherical surfaces were conventionally polished and finished in the ultraprecision method, respectively. Primary and secondary mirrors were aligned by using interferometer, resulting in residual wave-front errors of P-V 2.7μm and RMS 0.61μm, respectively. To avoid and minimize any misalignment, lenses assembled were confirmed with de-centering measurement tool from Tri-Optics. As one of the key optical design concepts, afocal beam from primary and secondary mirrors combined made much less sensitive the alignment process between mirrors and relay lenses. As the optical performance test, the FWHM of PSF was measured about 16μm at the room temperature, and the IR sensor was successfully aligned in the optimized position at the cryogenic temperature. Finally, wavelength calibration was executed by using monochromatic IR sources. To support the complication of optical configuration, the opto-mechanical structure was optimized to endure the launching condition and the space environment. We confirmed that the optical performance can be maintained after the space environmental test. In this paper, we present the development of optical system of NISS from optical design to performance test and calibration.

We present the KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC) targeting 14 clusters at 0.015 < z < 0.144 using the Inamori Magellan Areal Camera and Spectrograph on the 6.5-meter Magellan Baade telescope and the MegaCam on the 3.6-meter Canada-France-Hawaii Telescope. We provide a catalog of cluster galaxies that lists magnitudes, redshifts, morphologies, bulge-to-total ratios, and local density. Based on the 1409 spectroscopically-confirmed cluster galaxies brighter than -19.8 in the r-band, we study galaxy morphology, color, and visual features generated by galaxy mergers. We see a clear trend between morphological content and cluster velocity dispersion, which was not presented by previous studies using local clusters. Passive spirals are preferentially found in a highly dense region (i.e., cluster center), indicating that they have gone through the environmental quenching. In deep images (mu_r ~ 27 mag/"^2), 20% of our sample show signatures of recent mergers, which is not expected from theoretical predictions and a low frequency of ongoing mergers in our sample (~ 4%). Such a high fraction of recent mergers in the cluster environment supports a scenario that the merger events that made the features have preceded the galaxy accretion into the cluster environment. We conclude that mergers affect a cluster population mainly through the pre-processing on recently accreted galaxies., 21 pages, 19 figures, and 10 tables; Accepted for publication in ApJS

In hierarchical galaxy formation models, galaxies evolve through mergers and accretions. Tidally-disrupted debris from these processes can remain as diffuse, faint structures, which can provide useful insight into the assembly history of galaxies. To investigate the properties of the faint structures in outskirts of nearby galaxies, we conduct deep and wide-field imaging survey with KMTNet. We present our observing strategy and optimal data reduction process to recover the faint extended features in the imaging data of NGC 1291 taken with KMTNet. Through the dark sky flat-fielding and optimal sky subtraction, we can effectively remove inhomogeneous patterns. In the combined images, the peak-to-peak global sky gradients were reduced to less than $\sim0.5$% and $\sim0.3$% of the original $B$- and $R$-band sky levels, respectively. However, we find local spatial fluctuations in the background sky which can affect the precise measurement of the sky value. Consequently, we can reach the surface brightness of $\mu_{B,1\sigma} \sim$ 29.5 and $\mu_{R,1\sigma}\sim$ 28.5 mag arcsec$^{-2}$ in azimuthally averaged one-dimensional surface brightness profiles, that is mainly limited by the uncertainty in the sky determination. These results suggest that the deep imaging data produced by KMTNet are suitable to study the faint features of nearby galaxies such as outer disks and dwarf companions, but unideal (not impossible) to detect stellar halos. The one-dimensional profile revealed that NGC 1291 appeared to have Type I disk out to $R$ $\sim$ 30 kpc with no obvious color gradient and excess light due to a stellar halo was undetected., Comment: 8 pages, 10 figures, accepted to AJ

CXO J133815.6+043255 is an ultraluminous X-ray source (ULX) with ultraviolet, optical, and radio counterparts located 10 kpc away from the nucleus of the galaxy NGC 5252. Optical spectroscopic studies indicate that the ULX is kinematically associated with NGC 5252; yet, the compactness of its radio emission could not rule out the possibility that the ULX is a background blazar. We present follow-up VLBA radio observations that are able to resolve the compact radio emission of the ULX into two components, making the blazar scenario very unlikely. The east component is extended at 4.4 GHz and its detection also at 7.6 GHz reveals a steep spectral index. The west component is only detected at 4.4 GHz, is not firmly resolved, and has a flatter spectral index. Considering that the west component hosts the radio core, we constrain the black hole mass of the ULX to $10^{3.5} < M_\mathrm{BH} \lesssim 2 \times 10^{6}$ M$_{\odot}$ and its Eddington ratio to $\sim 10^{-3}$. The ULX is thus most likely powered by an intermediate-mass black hole or low-mass AGN. Our results constitute the first discovery of a multi-component radio jet in a ULX and possible intermediate-mass black hole., Accepted to MNRAS Letters

We present detailed image analysis of rest-frame optical images of 235 low-redshift ($z \leq$ 0.35) type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope. The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetry of the light distribution of the stars, as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H$\beta$ FWHM $\leq 2000$ km~s$^{-1}$) type 1 AGNs, in contrast to their broad-line (H$\beta$ FWHM $> 2000$ km~s$^{-1}$) counterparts, are preferentially hosted in later type, lower luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests narrow-line type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier type (bulge-dominated), more massive hosts, although a minority of them appears to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population., Comment: Published in ApJS

Studies of cluster galaxies are increasingly finding galaxies with spectacular one-sided tails of gas and young stars, suggestive of intense ram-pressure stripping. These so-called "jellyfish" galaxies typically have late-type morphology. In this paper, we present MUSE observations of an elliptical galaxy in Abell 2670 with long tails of material visible in the optical spectra, as well as blobs with tadpole-like morphology. The spectra in the central part of the galaxy reveals a stellar component as well as ionized gas. The stellar component does not have significant rotation, while the ionized gas defines a clear star-forming gas disk. We argue, based on deep optical images of the galaxy, that the gas was most likely acquired during a past wet merger. It is possible that the star-forming blobs are also remnants of the merger. In addition, the direction and kinematics of the one-sided ionized tails, combined with the tadpole morphology of the star-forming blobs, strongly suggests that the system is undergoing ram pressure from the intracluster medium. In summary, this paper presents the discovery of a post-merger elliptical galaxy undergoing ram pressure stripping., 6 pages, 5 figures, accepted for publication in ApJL

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved an almost daily cadence with observations from five ground-based telescopes. The H$\beta$ and He II $\lambda$4686 broad emission-line light curves lag that of the 5100 $\AA$ optical continuum by $4.17^{+0.36}_{-0.36}$ days and $0.79^{+0.35}_{-0.34}$ days, respectively. The H$\beta$ lag relative to the 1158 $\AA$ ultraviolet continuum light curve measured by the Hubble Space Telescope is roughly $\sim$50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is $\sim$50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for H$\beta$ and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the H$\beta$ and He II $\lambda$4686 emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for C IV, Ly $\alpha$, He II(+O III]), and Si IV(+O IV]) during the same monitoring period. Finally, given the optical luminosity of NGC 5548 during our campaign, the measured H$\beta$ lag is a factor of five shorter than the expected value implied by the $R_\mathrm{BLR} - L_\mathrm{AGN}$ relation based on the past behavior of NGC 5548., Comment: 22 pages, 13 figures, accepted to ApJ

Active galactic nuclei (AGNs) show a correlation between the size of the broad line region (BLR) and the monochromatic continuum luminosity at 5100 \AA, allowing black hole mass estimation based on single-epoch spectra. However, the validity of the correlation is yet to be clearly tested for high-luminosity AGNs. We present the first reverberation-mapping results of the Seoul National University AGN monitoring program (SAMP), which is designed to focus on luminous AGNs for probing the high end of the size-luminosity relation. We report time lag measurements of two AGNs, namely, 2MASS J10261389+5237510 and SDSS J161911.24+501109.2, using the light curves obtained over a $\sim$1000 day period with an average cadence of $\sim$10 and $\sim$20 days, respectively for photometry and spectroscopy monitoring. Based on a cross-correlation analysis and H$\beta$ line width measurements, we determine the H$\beta$ lag as $41.8^{+4.9}_{-6.0}$ and $52.6^{+17.6}_{-14.7}$ days in the observed-frame, and black hole mass as $3.65^{+0.49}_{-0.57} \times 10^7 M_{\odot}$ and $23.02^{+7.81}_{-6.56} \times 10^7 M_{\odot}$, respectively for 2MASS J1026 and SDSS J1619., Comment: 14 pages; accepted by ApJ

We report the results of an investigation to determine the nature of the offset active galactic nucleus (AGN) found in the source CXO J101527.2+625911. Hubble Space Telescope and Chandra X-ray observatory data had suggested that the offset AGN, which has an angular separation of only 0\farcs26 from the center of the host galaxy, is a recoiled Super Massive Black Hole (rSMBH). We carried out high angular resolution observations with both the VLBA (1.54 GHz) and the VLA (10.0 GHz \& 33.0 GHz) and detected a single compact radio source in the center of the host galaxy, with no radio continuum emission associated with the offset AGN. The detected radio source has a high brightness temperature value of $T_b=7.2\times10^{7}$ K, indicating that the radio emission is associated with an AGN. Furthermore, we present the decomposition of high-resolution KECK spectra of the [O III]5007��line into two narrow emission line components, which is a characteristic sign of a dual black hole system. These new radio and optical wavelength results suggest that CXO J101527.2+625911 is the host of a dual black hole system rather than a rSMBH., ApJ accepted

We investigate the triggering mechanism and the structural properties of obscured luminous active galactic nuclei from a detailed study of the rest-frame $B$ and $I$ HST images of 29 nearby ($z\approx 0.04-0.4$) optically selected type 2 quasars. Morphological classification reveals that only a minority (34%) of the hosts are mergers or interacting galaxies. More than half (55%) of the hosts contain regular disks, and a substantial fraction (38%), in fact, are disk-dominated ($B/T\lesssim 0.2$) late-type galaxies with low Sersic indices ($n < 2$), which is characteristic of pseudo bulges. The prevalence of bars in the spiral host galaxies may be sufficient to supply the modest fuel requirements needed to power the nuclear activity in these systems. Nuclear star formation seems to be ubiquitous in the central regions, leading to positive color gradients within the bulges and enhancements in the central surface brightness of most systems., 26 pages, 11 figures. Accepted by ApJ

The NISS (Near-infrared Imaging Spectrometer for Star formation history) is the near-infrared instrument optimized to the first next generation of small satellite (NEXTSat-1) in Korea. The spectro-photometric capability in the near-infrared range is a unique function of the NISS. The major scientific mission is to study the cosmic star formation history in local and distant universe. For those purposes, the NISS will perform the large areal imaging spectroscopic survey for astronomical objects and low background regions. We have paid careful attention to reduce the volume and to increase the total throughput. The newly implemented off-axis optics has a wide field of view (2° x 2°) and a wide wavelength range from 0.9 to 3.8μm. The mechanical structure is designed to consider launching conditions and passive cooling of the telescope. The compact dewar after relay-lens module is to operate the infrared detector and spectral filters at 80K stage. The independent integration of relay-lens part and primary-secondary mirror assembly alleviates the complex alignment process. We confirmed that the telescope and the infrared sensor can be cooled down to around 200K and 80K, respectively. The engineering qualification model of the NISS was tested in the space environment including the launch-induced vibration and shock. The NISS will be expected to demonstrate core technologies related to the development of the future infrared space telescope in Korea.

We use new precision measurements of black hole masses from water megamaser disks to investigate scaling relations between macroscopic galaxy properties and supermassive black hole (BH) mass. The megamaser-derived BH masses span 10^6-10^8 M_sun, while all the galaxy properties that we examine (including stellar mass, central mass density, central velocity dispersion) lie within a narrow range. Thus, no galaxy property correlates tightly with M_BH in ~L* spiral galaxies. Of them all, stellar velocity dispersion provides the tightest relation, but at fixed sigma* the mean megamaser M_BH are offset by -0.6+/-0.1 dex relative to early-type galaxies. Spiral galaxies with non-maser dynamical BH masses do not show this offset. At low mass, we do not yet know the full distribution of BH mass at fixed galaxy property; the non-maser dynamical measurements may miss the low-mass end of the BH distribution due to inability to resolve the spheres of influence and/or megamasers may preferentially occur in lower-mass BHs., 6 pages, 4 figures, replaced to fix error: NGC 4594 is not a maser galaxy

We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 to 9157 angstroms) combine simultaneous HST , Swift , and ground-based observations over a 180 day period from 2014 January to July. Light-curve variability is interpreted as the reverberation response of the accretion disk to irradiation by a central time-varying point source. Our model yields the disk inclination, i, temperature T1 at 1 light day from the black hole, and a temperature-radius slope, alpha. We also infer the driving light curve and find that it correlates poorly with both the hard and soft X-ray light curves, suggesting that the X-rays alone may not drive the ultraviolet and optical variability over the observing period. We also decompose the light curves into bright, faint, and mean accretion-disk spectra. These spectra lie below that expected for a standard blackbody accretion disk accreting at L/LEdd = 0.1, Comment: V2: Oops wrong title! V1: Accepted for publication in ApJ, 20 Pages, 11 Figures

We present a study of the optical spectral properties of 115 ultraluminous infrared galaxies (ULIRGs) in the southern sky. Using the optical spectra obtained at CTIO 4 m and provided by the 2dF Galaxy Redshift Survey and the 6dF Galaxy Survey, we measure emission line widths and fluxes for spectral classification. We determine the spectral types of ULIRGs with H_alpha measurement using the standard diagnostic diagrams. For ULIRGs without H_alpha measurement, we determine their spectral types using the plane of flux ratio between [OIII]_lambda5007 and H_beta versus [OIII] line width based on our new empirical criterion. This criterion is efficient to distinguish active galactic nuclei (AGNs) from non-AGN galaxies with completeness and reliability of about 90 per cent. The sample of 115 ULIRGs is found to consist of 8 broad-line AGNs, 49 narrow-line AGNs, and 58 non-AGNs. The AGN fraction is on average 50 per cent and increases with infrared luminosity and IRAS 25-60 micron colour, consistent with previous studies. The IRAS 25-60 micron colour distributions are significantly different between AGN and non-AGN ULIRGs, while their IRAS 60-100 micron colour distributions are similar.

We have measured and analyzed the dark data of two PICNIC IR arrays (P574 and P560) obtained through the Cosmic Infrared Background ExpeRiment (CIBER). First, we identified three types of bad pixels: the cold, the hot, and the transient, which are figured in total as 0.06% for P574 and 0.19% for P560. Then, after the bad pixels were masked, we determined the dark noise to be 20.5 ± 0.05 e^- and 16.1 ± 0.05 e^-, and the dark current to be 0.6 ± 0.05 e^-/sec and 0.7 ± 0.05 e^-/sec for P574 and P560, respectively. Finally, we discussed glitches and readout modes for a future mission.