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Database technology has been developing to exploit the next-generation hardware in the era of big data processing. At the same time, astronomical data size has been steadily increasing, and astronomical source catalogs obtained from largescale surveys with a wide-field camera, such as Subaru/Hyper Suprime-Cam (HSC), are a good test bench for evaluating the new database technology with a large data set. Such archive systems often employ a highly versatile relational database management system (RDBMS), but reducing the time required for data transaction and complex analysis has come to an important challenge. To tackle this difficulty, we aim to develop astronomical applications with a new catalog database using a next-generation RDBMS technology, where the query engine is designed to efficiently use computing infrastructures for processing big data. Demonstrations with science applications are essential to evaluate the new database. We verify query performance with the current HSC source catalog. For application to huge astronomical catalog databases, we are pursuing and verifying the capabilities of new database technologies. It will, in turn, enable fast ad hoc search and efficient detection of a wide range of variable events with the technology. Our pilot tests using typical astronomical queries on a cluster system shows significant improvements in response times with the aid of distributed query engines. We report performance of the test database for typical astronomical queries, and discuss optimizing the schema based on query workloads.

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2m Subaru telescope on the summit of Maunakea 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 deg$^2$ in five broad bands ($grizy$), with a $5\,\sigma$ point-source depth of $r \approx 26$. The Deep layer covers a total of 26~deg$^2$ 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 deg$^2$). 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., Comment: 14 pages, 7 figures, 5 tables. Corrected for a typo in the coordinates of HSC-Wide spring equatorial field in Table 5

We study the extent to which very bright (-23.0 < MUV < -21.75) Lyman-break selected galaxies at redshifts z~7 display detectable Lya emission. To explore this issue, we have obtained follow-up optical spectroscopy of 9 z~7 galaxies from a parent sample of 24 z~7 galaxy candidates selected from the 1.65 sq.deg COSMOS-UltraVISTA and SXDS-UDS survey fields using the latest near-infrared public survey data, and new ultra-deep Subaru z'-band imaging (which we also present and describe in this paper). Our spectroscopy has yielded only one possible detection of Lya at z=7.168 with a rest-frame equivalent width EW_0 = 3.7 (+1.7/-1.1) Angstrom. The relative weakness of this line, combined with our failure to detect Lya emission from the other spectroscopic targets allows us to place a new upper limit on the prevalence of strong Lya emission at these redshifts. For conservative calculation and to facilitate comparison with previous studies at lower redshifts, we derive a 1-sigma upper limit on the fraction of UV bright galaxies at z~7 that display EW_0 > 50 Angstrom, which we estimate to be < 0.23. This result may indicate a weak trend where the fraction of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7. Our results also leave open the possibility that strong Lya may still be more prevalent in the brightest galaxies in the reionization era than their fainter counterparts. A larger spectroscopic sample of galaxies is required to derive a more reliable constraint on the neutral hydrogen fraction at z~7 based on the Lya fraction in the bright galaxies., Comment: 20 pages, 7 figures, accepted for publication in ApJ

We present multi-waveband optical imaging data obtained from observations of the Subaru/XMM-Newton Deep Survey (SXDS). The survey field, centered at R.A.=02:18:00, decl.=-05:00:00, has been the focus of a wide range of multi-wavelength observing programs spanning from X-ray to radio wavelengths. A large part of the optical imaging observations are carried out with Suprime-Cam on Subaru Telescope at Mauna Kea in the course of Subaru Telescope Observatory Projects. This paper describes our optical observations, data reduction and analysis procedures employed, and the characteristics of the data products. A total area of 1.22 sqdeg is covered in five contiguous sub-fields, each of which corresponds to a single Suprime-Cam field of view (34'x27'), in five broad-band filters B, V, Rc, i', z' to the depths of B=28.4, V=27.8, Rc=27.7, i'=27.7 and z'=26.6 (AB, 3-sigma, 2-arcsec aperture). The data are reduced and compiled into five multi-waveband photometric catalogs, separately for each Suprime-Cam pointing. The i'-band catalogs contain about 900,000 objects, making the SXDS catalogs one of the largest multi-waveband catalogs in corresponding depth and area coverage. The SXDS catalogs can be used for an extensive range of astronomical applications such as the number density of the Galactic halo stars to the large scale structures at the distant universe. The number counts of galaxies are derived and compared with those of existing deep extragalactic surveys. The optical data, the source catalogs, and configuration files used to create the catalogs are publicly available via the SXDS web page (this http URL)

We report an on-going blank-field multi-wavelength deep and wide survey of the Subaru/ XMM - Newton Deep Survey Field (SXDF). The SXDF has been the focus of a wide range of multi-wavelength observing programs spanning the X-ray to the radio. These observations cover a large enough area (the initial optical imaging covers $\sim$ 1.3 deg $^{2}$ ) and depth ( $B=28.2$ ) that they are not affected by large-scale structures (which exist on tens of Mpc scales) and allow us to study the distribution and evolution of high- $z$ galaxies and AGNs, and thus constrain theories for their formation. Our early results include: i) an indication of the primeval Large Scale Structure (LSS) at z $\sim$ 5.7, ii) an indication for the down-sizing of galaxy formation at z $\sim$ 1, iii) identifications of passively evolving systems, and evidence for early formation and the passive evolution of present-day early-type galaxies, and iv) discovery of a large number of optically obscured QSOs. As for the next step forward - we express our hope to use the next generation optical/IR Extremely Large Telescopes (ELTs) to obtain larger and deeper spectroscopy samples of the high- $z$ objects.

We investigate mass-dependent galaxy evolution based on a large sample of (more than 50,000) K-band selected galaxies in a multi-wavelength catalog of the Subaru/XMM-Newton Deep Survey (SXDS) and the UKIRT Infrared Deep Sky Survey (UKIDSS)/Ultra Deep Survey (UDS). We employ the optical to near-infrared photometry to determine photometric redshifts of these galaxies. Then, we estimate the stellar mass of our sample galaxies using a standard fitting procedure. From the sample galaxies, we obtain the stellar mass function of galaxies and the cosmic stellar mass density up to z, Comment: 13 pages, 13 figures, 2 tables

We investigate mass-dependent galaxy evolution based on a large sample of, about 50,000, K-band selected galaxies in a multi-wavelength catalog of the Subaru/XMM- Newton Deep Survey (SXDS) and the UKIRT Infrared Deep Sky Survey (UKIDSS), Ultra Deep Survey (UDS). After we discriminate galaxies from stars and various false objects, we employ the optical to near-infrared photometry to determine photometric redshifts of these galaxies. Then, we estimate the stellar mass of our sample galaxies using the same standard fitting procedure as used for estimate the photometric redshift (photo-z). Since we employ exactly the same SED models both in the photo-z determination and mass estimation, stellar masses of galaxies thus obtained are internally consistent with the photo-z and other physical parameters of the best-fit SEDs, including age, metallicity, extinction due to the internal dust, etc. We compute the stellar mass function and the stellar mass density (SMD) up to redshift z=4. By combining a large number of stellar masses and spatial distributions of galaxies in one contiguous wide and deep field, we examine properties of the mass-dependent clustering of galaxies. Compared to previous studies, we are able to estimate stellar mass functions more accurately over the wider redshift range and, also, we can investigate properties of the K-selected galaxies to much lower-mass galaxies (M*~1010.5MΘ) at high-z (up to 3≦z The clustering properties derived from our data are relatively free from the field-to-field variation with the aid of the wide survey area. This enables us to investigate not only the evolution of stellar mass of galaxies but also the clustering evolution of galaxies as a function of the stellar mass up to the redshift z = 4. In order to discuss the clustering properties of the galaxies quantitatively, we derive the two-point angular correlation functions (ACFs) w(θ), using the technique proposed by Landy & Szalay (1993). The ACF shows the clustering properties of galaxies projected on the sky. From a given angular clustering measurement, the correlation length r0 of galaxies for each mass range can be estimated by the Limber equation (Limber 1953) using the redshift distribution of galaxies and a choice of cosmology (e.g., Peebles 1980). Since the spatial correlation function (SCF) obtained from a combination of w(θ) and the redshift distribution of sample galaxies should reflect the intrinsic clustering in the space, r0 shows the spatial clustering strength of sample galaxies. An observed trend we found is in good agreement with the local scaling behavior of the clustering with stellar mass of galaxies. More massive galaxies have stronger clustering at z10.5MΘ10.9 MΘ) may also be hosted in somewhat lower-mass DHs at the various different redshifts. We find that the turning redshift point of changing the dark matter haloes hosting the intermediate-mass galaxies is at z~2. We also find several high mass density regions of massive galaxies at 1.4≦z1011.3 MΘ ). Thus, the massive galaxies at this epoch are dominated by the massive sBzK galaxies. These high mass-density regions may be the proto-clusters which evolve into the present-day massive clusters of galaxies. We also find that the average stellar mass of the pBzK galaxies at 1.4≦z10.8 MΘ. Although this average mass corresponds to that of the intermediate-mass galaxies, the clustering strength of the whole pBzK population is as high as that of the massive galaxies (M*≧1011 MΘ). This result may suggest that the clustering structure of pBzK galaxies formed earlier than that of the sBzK galaxies at 1.4≦z