We present an IGM H i tomographic map in a survey volume of 16 × 19 × 131 h-3 commoving Mpc3 (cMpc3) centered at MAMMOTH-1 nebula and three neighboring quasars at z = 2.3. The MAMMOTH-1 nebula is an enormous Lyα nebula (ELAN), hosted by a type-II quasar dubbed MAMMOTH1-QSO, that extends over 1 h-1 cMpc with no clear physical origin. Here we investigate the H i-gas distribution around MAMMOTH1-QSO with the ELAN and three neighboring type-I quasars, making the IGM H i tomographic map with a spatial resolution of 2.6 h -1 cMpc. Our H i tomographic map is reconstructed with H i Lyα 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 H i overdensity for MAMMOTH1-QSO, and find that MAMMOTH1-QSO resides in a volume with fairly weak H i absorption. This suggests that MAMMOTH1-QSO may have a proximity zone where quasar illuminates and photoionizes the surrounding H i gas and suppresses H i absorption, and that the ELAN is probably a photoionized cloud embedded in the cosmic web. The H i radial profile of MAMMOTH1-QSO is very similar to those of three neighboring type-I quasars at z = 2.3, which is compatible with the AGN unification model. We compare the distributions of the H i absorption and star-forming galaxies in our survey volume, and identify a spatial offset between density peaks of star-forming galaxies and H i gas. This segregation may suggest anisotropic UV background radiation created by star-forming galaxy density fluctuations.

We search for galaxies with a strong Balmer break (Balmer break galaxies; BBGs) at z 6 over a 0.41 deg2 effective area in the COSMOS field. Based on rich imaging data, including data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), three candidates are identified by their extremely red K [3.6] colors, as well as by nondetection in the X-ray, optical, far-infrared, and radio bands. The nondetection in the deep ALMA observations suggests that they are not dusty galaxies but BBGs at z 6, although contamination from active galactic nuclei at z 0 cannot be completely ruled out for the moment. Our spectral energy distribution analyses reveal that the BBG candidates at z 6 have stellar masses of x 101 M, dominated by old stellar populations with ages of > 700 Myr. Assuming that all three candidates are real BBGs at z 6, we estimate the stellar mass density to be 2.411 x 104 M. Mpc-3. This is consistent with an extrapolation from the lower-redshift measurements. The onset of star formation in the three BBG candidates is expected to be several hundred million yr before the observed epoch of z 6. We estimate the star formation rate density (SI-RD) contributed by progenitors of the BBGs to be 2.4-12 x 10-5 Mc, yr-1 Mpc3 at z > 14 (99.7% confidence range). Our result suggests a smooth evolution of the SFRD beyond z = 8.

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey.

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most important outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope, and it started in 2014 March. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7yr of observations (61.5 nights), and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i ∼ 26.4, ∼26.5, and ∼27.0mag, respectively (5a for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0".6 in the i band in the Wide layer. We show that we achieve 1%-2% point spread function (PSF) photometry (root mean square) both internally and externally (against Pan-STARRS1), and ∼10mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online.

We conduct a systematic study of galactic outflows in star-forming galaxies at z ∼ 0-2 based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck (Erb et al.). We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at z ∼ 0-2 and perform the multicomponent fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (vmax) and central (vout) outflow velocities and estimate the mass loading factors (η), a ratio of the mass outflow rate to the star formation rate (SFR). Investigating the redshift evolution of the outflow velocities measured with the absorption lines whose depths and ionization energies are similar (Na I D and Mg I at z ∼ 0-1
Mg II and C II at z ∼ 1-2), we identify, for the first time, that the average value of vmax (vout) significantly increases by 0.05-0.3 dex from z ∼ 0 to 2 at a given SFR. Moreover, we find that the value of η increases from z ∼ 0 to 2 by η ∝ (1 + z)1.2±0.3 at a given halo circular velocity vcir, albeit with a potential systematics caused by model parameter choices. The redshift evolution of vmax (vout) and η is consistent with the galaxy-size evolution and the local velocity-SFR surface density relation and explained by high gas fractions in high-redshift massive galaxies, which is supported by recent radio observations. We obtain a scaling relation of η ∝ νcira for a = -0.2 ± 1.1 in our z ∼ 0 galaxies that agrees with the momentum-driven outflow model (a = -1) within the uncertainties.

We conduct a systematic search for galaxies at z = 0.1 1.5-with [O II]λ3727, [O III]λ5007, or Hal6563 emission lines extended over at least 30 kpc by using deep narrowband and broadband imaging in the-Subaru-XMM Deep Survey field. These extended emission-line galaxies are dubbed [O II], [O III], or Ha blobs. Based on a new selection method that securely selects-extended emission-line galaxies, we find 77 blobs at z = 0.40 1.46-with the isophotal area of emission lines down to 1.2 × 10-18 erg s-1 cm-2 kpc-2. Four of them are spectroscopically confirmed to be [O III] blobs at z=0.83. We identify AGN activities in eight blobs with X-ray and radio data, and find that the fraction of AGN contribution increases with increasing isophotal area of the extended emission. With the Kolmogorov-Smirnov (KS) and Anderson-Darling tests, we confirm that the stellar-mass distributions of Ha and [O II] blobs are not drawn from those of the emitters at the &gt
90% confidence level in that Ha and [O II] blobs are located at the massive end of the distributions, but cannot reject anull hypothesis of being the same distributions in terms of the specific star formation rates. It is suggested that galactic-scale outflows tend to be more prominent in more massive star-forming galaxies. Exploiting our sample homogeneously selected over the large area, we derive the number densities of blobs at each epoch. The number densities of blobs decrease drastically with redshifts at a rate that is larger than that of the decrease of cosmic star formation densities.