We study the UV luminosity functions (LFs) at \(z\sim 4\), \(5\), \(6,\) and \(7\) based on the deep large-area optical images taken by the Hyper Suprime-Cam (HSC) Subaru strategic program (SSP). On ...the 100 deg\(^2\) sky of the HSC SSP data available to date, we make enormous samples consisting of a total of 579,565 dropout candidates at \(z\sim 4-7\) by the standard color selection technique, 358 out of which are spectroscopically confirmed by our follow-up spectroscopy and other studies. We obtain UV LFs at \(z \sim 4-7\) that span a very wide UV luminosity range of \(\sim 0.002 - 100 \, L_{\rm UV}^\ast\) (\(-26 < M_{\rm UV} < -14\) mag) by combining LFs from our program and the ultra-deep Hubble Space Telescope legacy surveys. We derive three parameters of the best-fit Schechter function, \(\phi^\ast\), \(M_{\rm UV}^\ast\), and \(\alpha\), of the UV LFs in the magnitude range where the AGN contribution is negligible, and find that \(\alpha\) and \(\phi^\ast\) decrease from \(z\sim 4\) to \(7\) with no significant evolution of \(M_{\rm UV}^\ast\). Because our HSC SSP data bridge the LFs of galaxies and AGNs with great statistical accuracy, we carefully investigate the bright end of the galaxy UV LFs that are estimated by the subtraction of the AGN contribution either aided with spectroscopy or the best-fit AGN UV LFs. We find that the bright end of the galaxy UV LFs cannot be explained by the Schechter function fits at \(> 2 \sigma\) significance, and require either double power-law functions or modified Schechter functions that consider a magnification bias due to gravitational lensing.
(Abridged) We present results of Suzaku observations of the intracluster medium (ICM) in Abell 1689, combined with complementary analysis of the SDSS data and weak and strong lensing analysis of ...Subaru/Suprime-Cam and HST/ACS observations. Faint X-ray emission from the ICM around the virial radius is detected at 4.0 sigma significance. We find anisotropic gas temperature and entropy distributions in cluster outskirts correlated with large-scale structure of galaxies. The high temperature and entropy region in the northeastern (NE) outskirts is connected to an overdense filamentary structure. The outskirt regions in contact with low density void environments have low gas temperatures and entropies, deviating from hydrostatic equilibrium. These results suggest that thermalization of the ICM occurs faster along the filamentary structures than the void regions. A joint X-ray and lensing analysis shows that the hydrostatic mass is \(\sim60-90%\) of spherical lensing one but comparable to a triaxial halo mass within errors in \(0.6r_{2500} \simlt r \simlt 0.8r_{500}\), and that it is significantly biased as low as \(\simlt60%\) within \(0.4r_{2500}\), irrespective of mass models. The thermal gas pressure within \(r_{500}\) is, at most, \(\sim50\)--60% of the total pressure to balance fully the gravity of the spherical lensing mass, and \(\sim30\)--40% around the virial radius. Although these constitute lower limits when one considers the possible halo triaxiality, these small relative contributions of thermal pressure would require additional sources of pressure, such as bulk and/or turbulent motions.
Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Barro et al. 2011a, Paper I), we present a detailed SED analysis of nearly 80,000 IRAC 3.6+4.5 ...micron selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates separately for each galaxy in this large sample. The catalog includes 76,936 sources with 3.6 < 23.75 (85% completeness level of the IRAC survey) over 0.48 square degrees. The typical photometric redshift accuracy is Delta z/(1+z)=0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and IMFs in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 micron data available in the EGS. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z\(\gtrsim\)1.5 observed when only MIPS 24 micron data is available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the web-interface utility Rainbow-navigator
We present DLSCL J0916.2+2951 (z=0.53), a newly discovered major cluster merger in which the collisional cluster gas has become dissociated from the collisionless galaxies and dark matter. We ...identified the cluster using optical and weak lensing observations as part of the Deep Lens Survey. Our follow-up observations with Keck, Subaru, Hubble Space Telescope, and Chandra show that the cluster is a dissociative merger and constrain the dark matter self-interaction cross-section {\sigma}_{DM}m_{DM}^{-1}\leq7 cm^2g^{-1}. The system is observed at least 0.7\pm0.2 Gyr since first pass-through, thus providing a picture of cluster mergers 2-5 times further progressed than similar systems observed to date. This improved temporal leverage has implications for our understanding of merging clusters and their impact on galaxy evolution.
The Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. The primary goal of the survey is to catch the very early light of a SN, during the shock breakout phase. ...Detection of SN shock breakouts combined with multi-band photometry obtained with other facilities would provide detailed physical information on the progenitor stars of SNe. The survey is performed using a 2.2x2.2 deg field-of-view instrument on the 1.05-m Kiso Schmidt telescope, the Kiso Wide Field Camera (KWFC). We take a three-minute exposure in g-band once every hour in our survey, reaching magnitude g~20-21. About 100 nights of telescope time per year have been spent on the survey since April 2012. The number of the shock breakout detections is estimated to be of order of 1 during our 3-year project. This paper summarizes the KISS project including the KWFC observing setup, the survey strategy, the data reduction system, and CBET-reported SNe discovered so far by KISS.
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