Search Publications
The Stability of the Point-Spread Function of the Advanced Camera for Surveys on the Hubble Space Telescope and Implications for Weak Gravitational Lensing
Gardner, Jonathan P.; Ellis, Richard S.; Leauthaud, Alexie +11 more
We examine the spatial and temporal stability of the Hubble Space Telescope's Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) point-spread function (PSF) using the 2 deg2 COSMOS survey. This is important for studies of weak gravitational lensing, where the ability to deconvolve the PSF from galaxy shapes is of paramount import…
The XMM-Newton Wide-Field Survey in the COSMOS Field. II. X-Ray Data and the logN-logS Relations
Finoguenov, A.; Böhringer, H.; Fiore, F. +13 more
We present data analysis and X-ray source counts for the first season of XMM-Newton observations in the COSMOS field. The survey covers ~2 deg2 within the region of sky bounded by 09h57m30s<R.A.<10h03m30s, 01deg27'30''<decl.<02…
The Effects of Environment on Morphological Evolution at 0<z<1.2 in the COSMOS Survey
Mobasher, Bahram; Ellis, Richard S.; Capak, Peter +4 more
We explore the evolution of the morphology-density relation using the COSMOS Advanced Camera for Surveys (ACS) and previous cluster studies. The Gini parameter measured in a Petrosian aperture is found to be an effective way of selecting early-type galaxies free from systematic effects with redshift. We find that galaxies are transformed from late…
The Cosmic Evolution Survey (COSMOS): The Morphological Content and Environmental Dependence of the Galaxy Color-Magnitude Relation at z ~ 0.7
Taniguchi, Y.; Franceschini, A.; Capak, P. +11 more
We study the environmental dependence and the morphological composition of the galaxy color-magnitude diagram at z~0.7, using a pilot subsample of COSMOS. The sample includes ~2000 galaxies with IAB<24 and photometric redshift within 0.61<z<0.85, covering an area of 270 arcmin2. Galaxy morphologies are estimated via …
Search for Polarization from the Prompt Gamma-Ray Emission of GRB 041219a with SPI on INTEGRAL
Kouveliotou, C.; Baring, M. G.; Boggs, S. E. +2 more
Measuring the polarization of the prompt γ-ray emission from gamma-ray bursts (GRBs) can significantly improve our understanding of both the GRB emission mechanisms as well as the underlying engine driving the explosion. We searched for polarization in the prompt γ-ray emission of GRB 041219a with the SPI instrument on INTEGRAL. Using multiple-det…
The Evolution of the Number Density of Large Disk Galaxies in COSMOS
Kneib, J. -P.; Taniguchi, Y.; Sargent, M. T. +17 more
We study a sample of approximately 16,500 galaxies with IACS,AB<=22.5 in the central 38% of the COSMOS field, which are extracted from a catalog constructed from the Cycle 12 ACS F814W COSMOS data set. Structural information on the galaxies is derived by fitting single Sérsic models to their two-dimensional surface brightness distrib…
The XMM-Newton Wide-Field Survey in the COSMOS Field. IV. X-Ray Spectral Properties of Active Galactic Nuclei
Finoguenov, A.; Taniguchi, Y.; Fiore, F. +25 more
We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with eith…
The Intrinsically X-Ray-weak Quasar PHL 1811. II. Optical and UV Spectra and Analysis
Jenkins, Edward B.; Halpern, Jules P.; Leighly, Karen M. +1 more
This is the second of two papers reporting observations and analysis of the unusually bright (mb=14.4), luminous (MB=-25.5), nearby (z=0.192) narrow-line quasar PHL 1811. The first paper reported that PHL 1811 is intrinsically X-ray-weak and presented a spectral energy distribution (SED). Here we present HST STIS optical and …
A Bar Fuels a Supermassive Black Hole?: Host Galaxies of Narrow-Line Seyfert 1 Galaxies
Ohta, Kouji; Kawaguchi, Toshihiro; Aoki, Kentaro +1 more
We present optical images of nearby 50 narrow-line Seyfert 1 galaxies (NLS1s) that cover all the NLS1s at z<0.0666 and δ>=-25deg known in 2001. Among the 50 NLS1s, 40 images are newly obtained by our observations and 10 images are taken from archive data. Motivated by the hypothesis that NLS1s are in an early phase of a supermassi…
The Cosmic Evolution Survey (COSMOS): A Large-Scale Structure at z=0.73 and the Relation of Galaxy Morphologies to Local Environment
Finoguenov, A.; Böhringer, H.; Kneib, J. -P. +29 more
We have identified a large-scale structure at z~=0.73 in the COSMOS field, coherently described by the distribution of galaxy photometric redshifts, an ACS weak-lensing convergence map, and the distribution of extended X-ray sources in a mosaic of XMM-Newton observations. The main peak seen in these maps corresponds to a rich cluster with TX<…