Search

We present UV and Ly$α$ radial surface brightness (SB) profiles of Ly$α$ emitters (LAEs) at $z=2.84$ detected with the Hyper Suprime-Cam (HSC) on the Subaru Telescope. The depth of our data, together with the wide field coverage including a protocluster, enable us to study the dependence of Ly$α$ halos (LAHs) on various galaxy properties, including Mpc-scale environments. UV and Ly$α$ images of 3490 LAEs are extracted, and stacking the images yields SB sensitivity of $\sim1\times10^{-20}\mathrm{~erg~s^{-1}~cm^{-2}~arcsec^{-2}}$ in Ly$α$, reaching the expected level of optically thick gas illuminated by the UV background at $z\sim3$. Fitting of the two-component exponential function gives the scale-lengths of $1.56\pm0.01$ and $10.4\pm0.3$ pkpc. Dividing the sample according to their photometric properties, we find that while the dependence of halo scale-length on environment outside of the protocluster core is not clear, LAEs in the central regions of protoclusters appear to have very large LAHs which could be caused by combined effects of source overlapping and diffuse Ly$α$ emission from cool intergalactic gas permeating the forming protocluster core irradiated by active members. For the first time, we identify ``UV halos'' around bright LAEs which are probably due to a few lower-mass satellite galaxies. Through comparison with recent numerical simulations, we conclude that, while scattered Ly$α$ photons from the host galaxies are dominant, star formation in satellites evidently contributes to LAHs, and that fluorescent Ly$α$ emission may be boosted within protocluster cores at cosmic noon and/or near bright QSOs., 29 pages, 20 Figures, Accepted for publication in ApJ

We present 20,567 Ly$α$ emitters (LAEs) at $z=2.2-7.3$ that are photometrically identified by the SILVERRUSH program in a large survey area up to 25 deg$^2$ with deep images of five broadband filters (grizy) and seven narrowband filters targeting Ly$α$ lines at $z=2.2$, $3.3$, $4.9$, $5.7$, $6.6$, $7.0$, and $7.3$ taken by the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) and the Cosmic HydrOgen Reionization Unveiled with Subaru (CHORUS) survey. We select secure $>5σ$ sources showing narrowband color excesses via Ly$α$ break screening, taking into account the spatial inhomogeneity of limiting magnitudes. After removing spurious sources by careful masking and visual inspection of coadded and multi-epoch images obtained over the seven years of the surveys, we construct LAE samples consisting of 6,995, 4,642, 726, 6,124, 2,058, 18, and 5 LAEs at $z=2.2$, 3.3, 4.9, 5.7, 6.6, 7.0, and 7.3, respectively, although the $z=7.3$ candidates are tentative. Our LAE catalogs contain 241 spectroscopically confirmed LAEs at the expected redshifts from previous work. We demonstrate that the number counts of our LAEs are consistent with previous studies with similar LAE selection criteria. The LAE catalogs will be made public on our project webpage with detailed descriptions of the content and ancillary information about the masks and limiting magnitudes., 37 pages, 19 Figures, 5 Tables. Submitted to AAS Journals

著者人数: 18名, Accepted: 2019-09-02, 資料番号: SA1190151000

We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field with the DEep Imaging MultiObject Spectrograph (DEIMOS) on the Keck telescope, designed to tomographically map high-z HI gas through analysis of Lya absorption in background galaxies' spectra. In total, 198 galaxies were spectroscopically confirmed at 2.5 < z < 6 with a few low-z exceptions in the 26 x 15 arcmin^2 area, of which 148 were newly determined in this study. Our redshift measurements were merged with previously confirmed redshifts available in the 34 x 27 arcmin^2 area of the SSA22 field. This compiled catalog containing 730 galaxies of various types at z > 2 is useful for various applications, and it is made publicly available. Our SSA22-HIT survey has increased by approximately twice the number of spectroscopic redshifts of sources at z > 3.2 in the observed field. From a comparison with publicly available redshift catalogs, we show that our compiled redshift catalog in the SSA22 field is comparable to those among major extragalactic survey fields in terms of a combination of wide area and high surface number density of objects at z > 2. About 40 % of the spectroscopically confirmed objects in SSA22-HIT show reasonable quality of spectra in the wavelengths shorter than Lya when a sufficient amount of smoothing is adopted. Our data set enables us to make the HI tomographic map at z > 3, which we present in a parallel study., Accepted for publication in Astronomical Journal, 29 pages, 17 figures, 7 tables

We report the time variability of the late-time radio emission in a Type-I superluminous supernova (SLSN), PTF10hgi, at z = 0.0987. The Karl G. Jansky Very Large Array 3 GHz observations at 8.6 and 10 years after the explosion both detected radio emission with a ~40% decrease in flux density in the second epoch. This is the first report of a significant variability of the late-time radio light curve in a SLSN. Through combination with previous measurements in two other epochs, we constrained both the rise and decay phases of the radio light curve over three years, peaking at approximately 8-9 years after the explosion with a peak luminosity of L(3GHz) = 2 x 10^21 W/Hz. Possible scenarios for the origin of the variability are an active galactic nucleus (AGN) in the host galaxy, an afterglow caused by the interaction between an off-axis jet and circumstellar medium, and a wind nebula powered by a newly-born magnetar. Comparisons with models show that the radio light curve can be reproduced by both the afterglow model and magnetar wind nebula model. Considering the flat radio spectrum at 1-15 GHz and an upper limit at 0.6 GHz obtained in previous studies, plausible scenarios are a low-luminosity flat-spectrum AGN or a magnetar wind nebula with a shallow injection spectral index., Comment: 9 pages, 4 figures, accepted for publication in ApJ Letters

We present new spectroscopic observations of Lyman-$α$ (Ly$α$) Blob 2 ($z \sim$ 3.1). We observed extended Ly$α$ emission in three distinct regions, where the highest Ly$α$ surface brightness (SB) center is far away from the known continuum sources. We searched through the MOSFIRE slits that cover the high Ly$α$ SB regions, but were unable to detect any significant nebular emission near the highest SB center. We further mapped the flux ratio of the blue peak to the red peak and found it is anti-correlated with Ly$α$ SB with a power-law index of $\sim$ -0.4. We used radiative transfer models with both multiphase, clumpy and shell geometries and successfully reproduced the diverse Ly$α$ morphologies. We found that most spectra suggest outflow-dominated kinematics, while 4/15 spectra imply inflows. A significant correlation exists between parameter pairs, and the multiphase, clumpy model may alleviate previously reported discrepancies. We also modeled Ly$α$ spectra at different positions simultaneously and found that the variation of the inferred clump outflow velocities can be approximately explained by line-of-sight projection effects. Our results support the `central powering + scattering' scenario, i.e. the Ly$α$ photons are generated by a central powering source and then scatter with outflowing, multiphase HI gas while propagating outwards. The infalling of cool gas near the blob outskirts shapes the observed blue-dominated Ly$α$ profiles, but its energy contribution to the total Ly$α$ luminosity is less than 10%, i.e. minor compared to the photo-ionization by star-forming galaxies and/or AGNs., v1: 13 pages, 6 figures + Appendix. Submitted to MNRAS. v2: accepted version with moderate revision

We report results of a search for galaxies at z>3 with Lyman continuum (LyC) emission using a narrow-band filter NB359 with Subaru / Suprime-Cam in a ~800 arcmin$^2$ blank field around the GOODS-N. We use 103 star-forming galaxies (SFGs) and 8 AGNs with spectroscopic redshifts in a range between 3.06 and 3.5, and 157 photometrically selected z=3.1 Lyman $��$ emitter (LAE) candidates as the targets. After removing galaxies spectroscopically confirmed to be contaminated by foreground sources, we found two SFGs and one AGN as candidate LyC emitting sources among the targets with spectroscopic redshifts. Among LAE candidates, five sources are detected in the NB359 image, and three among them may be contaminated by foreground sources. We compare the sample galaxies in the GOODS-N with those in the SSA22, where a prominent protocluster at z=3.1 is known and the LyC search using the same NB359 filter has been made. Frequency of galaxies with LyC leakage in the SSA22 field may be about two times higher than the galaxies in the GOODS-N with the sample UV magnitude range, although the numbers of LyC detections in these fields are too small to make a statistically significant conclusion. By combining the sample galaxies in these fields, we place the 3$��$ upper limits of the observed LyC-to-UV flux density ratio and LyC escape fraction for galaxies at z=3.1 with absolute UV magnitude $M_{UV} < -18.8$ as ($f_{LyC}/f_{UV})_{obs} < 0.036$ and $f_{esc}^{abs}, 23 pages, 19 figures. Accepted for publication in MNRAS

We present an IGM HI tomography map in a survey volume of $16 \times 19 \times 131 \ h^{-3} {\rm comoving \ Mpc}^{3}$ (cMpc$^3$) centered at MAMMOTH-1 nebula and three neighbouring quasars at $z=2.3$. MAMMOTH-1 nebula is an enormous Ly$��$ nebula (ELAN), hosted by a type-II quasar dubbed MAMMOTH1-QSO, that extends over $1\ h^{-1}$ cMpc with not fully clear physical origin. Here we investigate the HI-gas distribution around MAMMOTH1-QSO with the ELAN and three neighbouring type-I quasars, making the IGM HI tomography map with a spatial resolution of $2.6\ h^{-1}$ cMpc. Our HI tomography map is reconstructed with HI Ly$��$ forest absorption of bright background objects at $z=2.4-2.9$: one eBOSS quasar and 16 Keck/LRIS galaxy spectra. We estimate the radial profile of HI flux overdensity for MAMMOTH1-QSO, and find that MAMMOTH1-QSO resides in a volume with significantly weak HI absorption. This suggests that MAMMOTH1-QSO has a proximity zone where quasar illuminates and photo-ionizes the surrounding HI gas and suppresses HI absorption, and that the ELAN is probably a photo-ionized cloud embedded in the cosmic web. The HI radial profile of MAMMOTH1-QSO is very similar to those of three neighbouring type-I quasars at $z=2.3$, which is compatible with the AGN unification model. We compare the distributions of the HI absorption and star-forming galaxies in our survey volume, and identify a spatial offset between density peaks of star-forming galaxies and HI gas. This segregation may suggest anisotropic UV background radiation created by star-forming galaxy density fluctuations., 15 pages, 9 figures. Accepted for Publication in ApJ

We report on the results of deep and wide-field (1.1 deg$^2$) narrow-band observations with Subaru/Hyper Suprime-Cam (HSC) of a field around a hyperluminous QSO (HLQSO), HS1549+1919, residing in a protocluster at $z=2.84$, to map the large-scale structure of Ly$��$ emitters (LAEs). One HSC pointing enables us to detect 3490 LAEs and 76 extended Ly$��$ blobs (LABs), probing diverse environments from voids to protoclusters. The HLQSO is found to be near the center of the protocluster, which corresponds to the intersection of $\sim$100 cMpc-scale structures of LAEs. LABs are basically distributed along the large-scale structure, with larger ones particularly clustered around the HLQSO, confirming a previously noted tendency of LABs to prefer denser environments. Moreover, the shapes of LABs near the HLQSO appear to be aligned with the large-scale structure. Finally, a deep Ly$��$ image reveals a diffuse Ly$��$ nebula along a filamentary structure with no luminous UV/sub-mm counterpart. We suggest that the diffuse nebula is due to a cold filament with high clumping factor illuminated by the QSO, with a required high clumpiness provided by unresolved residing halos of mass $\leq 10^{9-10}M_\odot$., 6 pages, 3 figures, submitted to PASJ

We present our new ALMA observations targeting [OIII]88um, [CII]158um, [NII]122um, and dust continuum emission for three Lyman break galaxies at z=6.0293-6.2037 identified in the Subaru/Hyper Suprime-Cam survey. We clearly detect [OIII] and [CII] lines from all of the galaxies at 4.3-11.8sigma levels, and identify multi-band dust continuum emission in two of the three galaxies, allowing us to estimate infrared luminosities and dust temperatures simultaneously. In conjunction with previous ALMA observations for six galaxies at z>6, we confirm that all the nine z=6-9 galaxies have high [OIII]/[CII] ratios of L[OIII]/L[CII]~3-20, ~10 times higher than z~0 galaxies. We also find a positive correlation between the [OIII]/[CII] ratio and the Lya equivalent width (EW) at the ~90% confidence level. We carefully investigate physical origins of the high [OIII]/[CII] ratios at z=6-9 using Cloudy, and find that high density of the interstellar medium, low C/O abundance ratio, and the cosmic microwave background attenuation are responsible to only a part of the z=6-9 galaxies. Instead, the observed high [OIII]/[CII] ratios are explained by 10-100 times higher ionization parameters or low photodissociation region (PDR) covering fractions of 0-10%, both of which are consistent with our [NII] observations. The latter scenario can be reproduced with a density bounded nebula with PDR deficit, which would enhance the Lya, Lyman continuum, and C+ ionizing photons escape from galaxies, consistent with the [OIII]/[CII]-Lya EW correlation we find., 20 pages, 18 figures, Accepted for publication in ApJ

We present CO J=4-3 line and 3 mm dust continuum observations of a 100 kpc-scale filamentary Ly{\alpha} nebula (SSA22 LAB18) at z=3.1 using the Atacama Large Millimeter/submillimeter Array (ALMA). We detected the CO J=4-3 line at a systemic z(CO)=3.093 {\pm} 0.001 at 11 {\sigma} from one of the ALMA continuum sources associated with the Ly{\alpha} filament. We estimated the CO J=4-3 luminosity of L'CO(4-3)=(2.3\pm0.2)x10^9 K km s^{-1} pc^2 for this CO source, which is one order of magnitude smaller than those of typical z>1 dusty star-forming galaxies (DSFGs) of similar far-infrared luminosity L(IR)~10^{12} Lsun. We derived a molecular gas mass of Mgas=(4.4^{+0.9}_{-0.6})x10^9 Msun and a star-formation rate of SFR=270\pm160 Msun yr^{-1}. We also estimated a gas depletion time of {\tau}(dep)=17\pm10 Myr, being shorter than those of typical DSFGs. It is suggested that this source is in a transition phase from DSFG to a gas-poor, early-type galaxy. From ALMA to Herschel multi-band dust continuum observations, we measured a dust emissivity index {\beta}=2.3\pm0.2, which is similar to those of local gas-poor, early-type galaxies. Such a high {\beta} can be reproduced by specific chemical compositions for interstellar dust at the submillimeter wavelengths from recent laboratory experiments. ALMA CO and multi-band dust continuum observations can constrain the evolutionary stage of high-redshift galaxies through {\tau}(dep) and {\beta}, and thus we can investigate dust chemical compositions even in the early Universe., Comment: 6 pagers, 3 figures

著者人数: 24名, Accepted: 2017-02-24, 資料番号: SA1170016000

We have carried out a panoramic Ly$��$ narrowband imaging with Suprime-Cam on Subaru towards the known protocluster USS1558--003 at $z=2.53$. Our previous narrowband imaging at near-infrared has identified multiple dense groups of H$��$ emitters (HAEs) within the protocluster. We have now identified the large-scale structures across a $\sim$50 comoving Mpc scale traced by Ly$��$ emitters (LAEs) in which the protocluster traced by the HAEs is embedded. On a smaller scale, however, there are remarkably few LAEs in the regions of HAE overdensities. Moreover, the stacking analyses of the images show that HAEs in higher-density regions show systematically lower escape fractions of Ly$��$ photons than those of HAEs in lower-density regions. These phenomena may be driven by the extra depletion of Ly$��$ emission lines along our line of sight by more intervening cold circumgalactic/intergalactic medium and/or dust existing in the dense core. We also caution that all the past high-$z$ protocluster surveys using LAEs as the tracers would have largely missed galaxies in the very dense cores of the protoclusters where we would expect to see any early environmental effects., 6 pages, 4 figures, accepted for publication in MNRAS Letter

We conduct a systematic search for galaxy protoclusters at $z\sim3.8$ based on the latest internal data release (S16A) of the Hyper SuprimeCam Subaru strategic program (HSC-SSP). In the Wide layer of the HSC-SSP, we investigate the large-scale projected sky distribution of $g$-dropout galaxies over an area of $121\,\mathrm{deg^2}$, and identify 216 large-scale overdense regions ($>4��$ overdensity significance) that are good protocluster candidates. Of these, 37 are located within $8\,\mathrm{arcmin}$ ($3.4\,\mathrm{physicalMpc}$) from other protocluster candidates of higher overdensity, and are expected to merge into a single massive structure by $z=0$. Therefore, we find 179 unique protocluster candidates in our survey. A cosmological simulation that includes projection effects predicts that more than 76\% of these candidates will evolve into galaxy clusters with halo masses of at least $10^{14}\,M_{\odot}$ by $z=0$. The unprecedented size of our protocluster candidate catalog allowed us to perform, for the first time, an angular clustering analysis of the systematic sample of protocluster candidates. We find a correlation length of $35.0\,h^{-1}\,\mathrm{Mpc}$. The relation between correlation length and number density of $z\sim3.8$ protocluster candidates is consistent with the prediction of the $��$CDM model, and the correlation length is similar to that of rich clusters in the local universe. This result suggests that our protocluster candidates are tracing similar spatial structures as those expected of the progenitors of rich clusters and enhances the confidence that our method to identify protoclusters at high redshifts is robust. In the coming years, our protocluster search will be extended to the entire HSC-SSP Wide sky coverage of $\sim1400\,\mathrm{deg^2}$ to probe cluster formation over a wide redshift range of $z\sim2\mathrm{-}6$., 11 pages, 8 figures, accepted for publication in PASJ special issue

著者人数: 18名, Accepted: 2016-05-19, 資料番号: SA1160054000

Lya nebulae, or "Lya blobs", are extended (up to ~100 kpc), bright (L[Lya] > 10^43 erg/s) clouds of Lya emitting gas that tend to lie in overdense regions at z ~ 2--5. The origin of the Lya emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband, imaging polarimetry of a radio-loud Lya nebula, B3 J2330+3927 at z=3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob's Lya emission peak and its radio lobes align roughly with the blob's major axis. With the SPOL polarimeter on the 6.5m MMT telescope, we map the total (Lya + continuum) polarization in a grid of circular apertures of radius 0.6" (4.4kpc), detecting a significant (>2sigma) polarization fraction P in nine apertures and achieving strong upper-limits (as low as 2%) elsewhere. P increases from, 9 pages, 7 figures, accepted for publication in ApJ

著者人数: 16名, Accepted: 2016-08-15, 資料番号: SA1160106000

We conducted a deep narrow-band imaging survey with the Subaru Prime Focus Camera on the Subaru Telescope and constructed a sample of Ly$��$ emitters (LAEs) at z=2.53 in the UDS-CANDELS field where a sample of H$��$ emitters (HAEs) at the same redshift is already obtained from our previous narrow-band observation at NIR. The deep narrow-band and multi broadband data allow us to find LAEs of stellar masses and star-formation rates (SFRs) down to $\gtrsim$$10^8$ M$_\odot$ and $\gtrsim$0.2 M$_\odot$/yr, respectively. We show that the LAEs are located along the same mass-SFR sequence traced by normal star-forming galaxies such as HAEs, but towards a significantly lower mass regime. Likewise, LAEs seem to share the same mass--size relation with typical star-forming galaxies, except for the massive LAEs, which tend to show significantly compact sizes. We identify a vigorous mass growth in the central part of LAEs: the stellar mass density in the central region of LAEs increases as their total galaxy mass grows. On the other hand, we see no Ly$��$ line in emission for most of the HAEs. Rather, we find that the Ly$��$ feature is either absent or in absorption (Ly$��$ absorbers; LAAs), and its absorption strength may increase with reddening of the UV continuum slope. We demonstrate that a deep Ly$��$ narrow-band imaging like this study is able to search for not only LAEs but also LAAs in a certain redshift slice. This work suggests that LAEs trace normal star-forming galaxies in the low-mass regime, while they remain as a unique population because the majority of HAEs are not LAEs., 20 pages, 18 figures, 3 tables, accepted for publication in MNRAS

We report a detailed modeling of a mass profile of a $z = 0.2999$ massive elliptical galaxy using 30 milli-arcsecond resolution 1-mm Atacama Large Millimeter/submillimeter Array (ALMA) images of the galaxy-galaxy lensing system SDP.81. The detailed morphology of the lensed multiple images of the $z = 3.042$ infrared-luminous galaxy, which is found to consist of tens of $\lesssim 100$-pc-sized star-forming clumps embedded in a $\sim 2$ kpc disk, are well reproduced by a lensing galaxy modeled by an isothermal ellipsoid with a 400 pc core. The core radius is consistent with that of the visible stellar light, and the mass-to-light ratio of $\sim 2\,M_{\odot}\,L_{\odot}^{-1}$ is comparable to the locally measured value, suggesting that the inner 1 kpc region is dominated by luminous matter. The position of the predicted mass centroid is consistent to within $\simeq 30$ mas with that of a non-thermal source detected with ALMA, which likely traces an active galactic nucleus of the foreground elliptical galaxy. A point source mass of $> 3 \times 10^8\,M_{\odot}$ mimicking a supermassive black hole is required to explain the non-detection of a central image of the background galaxy, although the black hole mass degenerates with the core radius of the elliptical galaxy. The required mass is consistent with that predicted from the well-known correlation between black hole mass and host velocity dispersion. Our analysis demonstrates the power of ALMA imaging of strong gravitational lensing for studying the innermost mass profiles and the central supermassive black hole of distant elliptical galaxies., Accepted for publication in PASJ; 7 pages, 4 figures, 1 table. The lens model is available at http://www.ioa.s.u-tokyo.ac.jp/~ytamura/SDP81/

We exploit wide-field Ly$alpha$ imaging with Subaru to probe the environment around TN J1338-1942, a powerful radio galaxy with a >100 kpc Ly$��$ halo at z=4.11. We used a sample of Ly$��$ emitters (LAEs) down to $\log(L_{\rm Ly��} [erg\, s^{-1}])\sim 42.8$ to measure the galaxy density around TNJ1338, compared to a control sample from a blank field taken with the same instrument. We found that TNJ1338 resides in a region with a peak overdensity of $��_{\rm LAE}=2.8\pm 0.5$ on scales of $8\, h^{-1}\rm Mpc$ (on the sky) and $112\, h^{-1}\rm Mpc$ (line of sight) in comoving coordinates. Adjacent to this overdensity, we found a strong underdensity where virtually no LAEs are detected. We used a semi-analytical model of LAEs derived from the Millennium Simulation to compare our results with theoretical predictions. While the theoretical density distribution is consistent with the blank field, overdense regions such as that around TNJ1338 are very rare, with a number density of $6.4\times 10^{-8}\rm Mpc^{-3}$ (comoving), corresponding to the densest < 0.4 percentile at $z\simeq 4.1$. We also found that the Ly$��$ luminosity function in the TNJ1338 field differs from that in the blank field: the number of bright LAEs ($\log(L_{\rm Ly��}[erg\,s^{-1}]) \gtrsim 43.3$) is enhanced, while the number of fainter LAEs is relatively suppressed. These results suggest that some powerful radio galaxies associated with Ly$��$ nebulae reside in extreme overdensities on $\sim 3$--$6\, \rm Mpc$ scales, where star-formation and AGN activity may be enhanced via frequent galaxy mergers or high rates of gas accretion from the surroundings., 20 papges, 9 figures (incl. appendix), accepted for publication in MNRAS

The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large scale structure at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a Cold Dark Matter (CDM) dominated universe predict that the IGM is distributed in a cosmic web of filaments, and that galaxies should form along and at the intersections of these filaments (Bond et al. 1994; Miralda-Escude et al. 1996). While observations of QSO absorption lines and the large scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web has never been confirmed by direct imaging. Here we report the Lyman-alpha blob 2 (LAB2) in SSA22, with the Cosmic Web Imager. This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hours of total source exposure, CWI has revealed that LAB2 has extended Lyman-alpha emission which is consistent with filaments. We perform tests to secure the robustness of this result, which relies on data with modest signal-to-noise ratio. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral-image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles of optically thick Lyman-alpha emission. The flux is 10 to 20x brighter than expected for the emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using emission models we infer a baryon mass in the filaments of at least 1-4x10e11 Solar Mass, and the dark halo mass is at least 2x10e12 Solar Mass. The spatial kinematic morphology is more consistent with inflow from the cosmic web than outflow. LAB2 and the surrounding gas have significant and coaligned angular momentum, strengthening the case for their association., Comment: 72 pages, 29 figures, accepted to the Astrophysical Journal (or Ap. J.)

We conduct a deep narrow-band imaging survey of 13 Ly$��$ blobs (LABs) located in the SSA22 proto-cluster at z~3.1 in the CIV and HeII emission lines in an effort to constrain the physical process powering the Ly$��$ emission in LABs. Our observations probe down to unprecedented surface brightness limits of 2.1 $-$ 3.4 $\times$ 10$^{-18}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ per 1 arcsec$^2$ aperture (5$��$) for the HeII$��$1640 and CIV$��$1549 lines, respectively. We do not detect extended HeII and CIV emission in any of the LABs, placing strong upper limits on the HeII/Ly$��$ and CIV/Ly$��$ line ratios, of 0.11 and 0.16, for the brightest two LABs in the field. We conduct detailed photoionization modeling of the expected line ratios and find that, although our data constitute the deepest ever observations of these lines, they are still not deep enough to rule out a scenario where the Ly$��$ emission is powered by the ionizing luminosity of an obscured AGN. Our models can accommodate HeII/Ly$��$ and CIV/Ly$��$ ratios as low as $\simeq$0.05 and $\simeq$0.07 respectively, implying that one needs to reach surface brightness as low as 1 $-$ 1.5 $\times$ 10$^{-18}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ (at 5$��$) in order to rule out a photoionization scenario. These depths will be achievable with the new generation of image-slicing integral field units such as VLT/MUSE or Keck/KCWI. We also model the expected HeII/Ly$��$ and CIV/Ly$��$ in a different scenario, where Ly$��$ emission is powered by shocks generated in a large-scale superwind, but find that our observational constraints can only be met for shock velocities $v_{\rm s} \gtrsim$ 250 km s$^{-1}$, which appear to be in conflict with recent observations of quiescent kinematics in LABs., 24 pages, 13 figures, submitted to ApJ

We present the results of our wide-field narrow band imaging of the field around the radio galaxy 53W002 at z = 2.390 with Subaru/Suprime-Cam. A custom made filter NB413 centered at 4140 �� with the width of 83 �� is used to observe the 31' x 24' area around the radio galaxy. We detected 204 Ly��emitters (LAEs) at z = 2.4 with a rest frame equivalent width larger than 25 �� to the depth of 26 AB mag (in NB413). The entire LAE population in the 53W002 field has an average number density and distributions of equivalent width and size that are similar to those of other fields at z ~ 2. We identify a significant high density region (53W002F-HDR) that spreads over ~ 5' x 4' near 53W002 where the LAE number density is nearly four times as large as the average of the entire field. Using the probability distribution function of density fluctuation, we evaluate the rareness probability of the 53W002F-HDR to be 0.9^{+2.4}_{-0.62}%, which corresponds to a moderately rich structure. No notable environmental dependency at the comoving scale of 10 Mpc is found for the distributions of the Ly��equivalent width and luminosity in the field. We also detected 4 Ly��blobs (LABs), one of which is newly discovered. They are all found to be located in the rims of high density regions. The biased location and unique morphologies in Ly��suggest that galaxy interaction play a key role in their formation., 26 pages, 12 figures

In order to constrain the bolometric luminosities, dust properties and molecular gas content of giant Lyman alpha nebulae, the so-called Lyman alpha blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ~ 3: a Lya blob discovered by its strong Spitzer MIPS 24um detection (LABd05; Dey et al. 2005) and the Steidel blob 1 (SSA22-LAB01; Steidel et al. 2000). We find that the spectral energy distribution of LABd05 is well described by an AGN-starburst composite template with L(FIR) = (4.0 +/- 0.5) x 10^12 Lsun, comparable to high-z sub-millimeter galaxies and ultraluminous infrared galaxies. New APEX/LABOCA 870um measurements rule out the reported SCUBA detection of the SSA22-LAB01 (S[850um] = 16.8 mJy) at the > 4sigma level. Consistent with this, ultra-deep Plateau de Bure Interferometer (PdBI) observations with ~2arcsec spatial resolution also fail to detect any 1.2mm continuum source down to ~0.45mJy per beam (3sigma). Combined with the existing (sub)mm observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of (Snu dV) < 0.25--1.0 Jy km/s, indicating a modest molecular gas reservoir, M(H_2) < 1--3 x 10^10 Msun. The non-detections exclude, with high significance (12 sigma), the previous tentative detection of a CO(4-3) line in the SSA22-LAB01. The increased sensitivity afforded by ALMA will be critical in studying molecular gas and dust in these interesting systems., Accepted for publication in ApJ, 10 pages, 7 figures

We present Keck spectroscopic observations of z>6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z'=27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Ly_alpha emission lines at 6< z < 6.4. The median value of the Ly_alpha rest-frame equivalent widths (EWs) is ~50 A, with four EWs >100 A. This well-defined spectroscopic sample spans a UV-continuum luminosity range of -21.8< M_{UV}~6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 56., 14 pages, 7 figures, accepted for publication in ApJ

This paper presents the results from the first wide and deep dual narrow-band survey to select H-alpha (Ha) and [OII] line emitters at z=1.47+-0.02 (using matched narrow-band filters in the H and z' bands), exploiting synergies between the UKIRT and Subaru telescopes. The Ha survey at z=1.47 reaches a flux limit of ~7x10^-17 erg/s/cm^2 and detects ~200 Ha emitters over 0.7deg^2, while the much deeper [OII] survey reaches an effective flux of ~7x10^-18 erg/s/cm^2, detecting ~1400 z=1.47 [OII] emitters in a matched co-moving volume of ~2.5x10^5 Mpc^3. The combined survey results in the identification of 190 simultaneous Ha and [OII] emitters at z=1.47. Ha and [OII] luminosity functions are derived and both are shown to evolve significantly from z~0 in a consistent way. The star formation rate density of the Universe at z=1.47 is evaluated, with the Ha analysis yielding 0.16+-0.05 M_sun/yr/Mpc^3 and the [OII] analysis 0.17+-0.04 M_sun/yr/Mpc^3. The measurements are combined with other studies, providing a self-consistent measurement of the star formation history of the Universe over the last ~11Gyrs. By using a large comparison sample at z~0.1 (from the SDSS), [OII]/Ha line ratios are calibrated as probes of dust-extinction. Ha emitters at z~1.47 show on average 1 mag of extinction at Ha, similar to the SDSS sources at z~0. Although we find that dust extinction correlates with SFR, the relation evolves by about ~0.5 mag from z~1.5 to z~0, with z~0 relations over-predicting the dust extinction corrections at high-z by that amount. Stellar mass is found to be a much more fundamental extinction predictor, with the relation between mass and extinction being valid at both z~0 and z~1.5. Dust extinction corrections as a function of optical colours are also derived, offering simpler mechanisms for estimating extinction in moderately star-forming systems over the last ~9Gyrs [Abridged]., Accepted for publication in MNRAS. Revised version following the reviewer's report. 21 pages, 23 figures

We made a narrowband NB973 (bandwidth of 200A at 9755A) imaging of the Subaru Deep Field (SDF) and found two z=7 Lyman alpha emitter (LAE) candidates down to NB973=24.9. Carrying out deep follow-up spectroscopy, we identified one of them as a real z=6.96 LAE. This has shown that galaxy formation was in progress just 750 Myr after the Big Bang. Meanwhile, the Lyman alpha line luminosity function of LAE is known to decline from z=5.7 to 6.6 in the SDF. L* at z=6.6 is 40-60% of that at z=5.7. We also confirm that the number density of z=7 LAE is only 17% of the density at z=6.6 comparing the latest SDF LAE samples. This series of significant decreases in LAE density with increasing redshift can be the result of galaxy evolution during these epochs. However, using the UV continuum luminosity functions of LAEs, those of Lyman break galaxies, and a LAE evolution model based on the hierarchical clustering, we find that galaxy evolution alone cannot explain all the decrease in density. This extra density deficit can be interpreted as the attenuation of the Lyman alpha photons from LAEs due to a rapid evolution of neutral hydrogen fraction during the ongoing cosmic reionization at z~6.6-7., published in Astrophysical Journal

We present the results of an intermediate resolution (~2 angstrom) spectroscopy of a sample of 37 candidate Lyman alpha blobs and emitters at redshift z=3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The emission lines are detected for all the 37 objects and have variety in their line profiles. The Lyman alpha velocity widths (FWHM) of the 28 objects with higher quality spectra, measured by fitting a single Gaussian profile, are in the range of 150 - 1700 km/s and correlate with the Lyman alpha spatial extents. All the 12 Lyman alpha blobs (>16 arcsec^2) have large velocity widths of > 500 km/s. While there are several possible physical interpretations of the Lyman alpha velocity widths (motion of gravitationally-bound gas clouds, inflows, merging of clumps, or outflows from superwinds), the large velocity widths of the Lyman alpha blobs suggest that they are the sites of massive galaxy formation. If we assume gravitationally-bound gas clouds, the dynamical masses of the Lyman alpha blobs are estimated to be ~10^12 - 10^13 Msun. Even for the case of outflows, the outflow velocities are likely to be the same order of the rotation velocities as inferred from the observational evidence for local starburst galaxies., Accepted for publication in ApJL

We present the results of a survey for emission-line objects based on optical intermediate-band ($\lambda_{\rm c}$ = 5736 \AA ~ and $\Delta\lambda$ = 280 \AA) and broad-band ($B$, $V$, $R$, and $i^\prime$) observations of the Subaru/XMM-Newton Deep Field on the 8.2 m Subaru telescope with the Subaru Prime Focus Camera, Suprime-Cam. All the data were obtained during the guaranteed time observations of the Suprime-Cam instrument. The intermediate-band image covered a sky area with 10\minpoint62 $\times 12\minpoint40 \approx 132$ arcmin$^2$ in the Subaru/XMM-Newton Deep Field (Ouchi et al.). Using this image, we have found 23 emission-line sources whose observed emission-line equivalent widths are greater than 250 \AA. Their optical multicolor properties indicate that six emission-line sources are Ly$\alpha$ emitters at $z \approx$ 3.7 ($\Delta z \approx 0.22$). They are either intense starburst galaxies or active galactic nuclei like quasars at $z \approx$ 3.7. Two more emission-line sources may also be Ly$\alpha$ emitters at $z \approx$ 3.7 although their multicolor properties are marginal. Among the remaining 15 emission-line objects, eight objects appear strong emission-line galaxies at lower redshift; e.g., [O {\sc ii}] $\lambda$3727 emitters at $z \approx 0.54$, H$\beta$ at $z \approx 0.18$, or [O {\sc iii}]$\lambda$5007 emitters at $z \approx 0.15$. The remaining seven objects are unclassified because they are too faint to be detected in broad-band images. We discuss observational properties of these strong emission-line sources. In particular, our data allow us to estimate the star formation density at $z \approx 3.7$ for the first time., Comment: Accepted for publication in AJ;14 pages, 26 figures (all figures are JPEG file)