Weak Gravitational Lensing with COSMOS: Galaxy Selection and Shape Measurements

By A.Leauthaud, R.Massey, J.-P.Kneib, J.Rhodes, D.E.Johnston, P.Capak, C.Heymans, R.S.Ellis, A.M.Koekemoer, O. Fèvre and 17 more. 2007

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With a primary goal of conducting precision weak-lensing measurements from space, the COSMOS survey has imaged the largest contiguous area observed by Hubble Space Telescope to date, using the Advanced Camera for Surveys (ACS). This is the first paper in a series in which we describe our strategy for addressing the various technical challenges in the production of weak-lensing measurements from COSMOS data. We first construct a source catalog from 575 ACS/WFC tiles (1.64 deg2) subsampled at a pixel scale of 0.03''. Defects and diffraction spikes are carefully removed, leaving a total of 1.2 × 106 objects to a limiting magnitude of F814W = 26.5. This catalog is made publicly available. Multiwavelength follow-up observations of the COSMOS field provide photometric redshifts for 73% of the source galaxies in the lensing catalog. We analyze and discuss the COSMOS redshift distribution and show broad agreement with other surveys to z ~ 1. Our next step is to measure the shapes of galaxies and correct them for the distortion induced by the time-varying ACS point-spread function and for charge transfer efficiency (CTE) effects. Simulated images are used to derive the shear susceptibility factors that are necessary in transforming shape measurements into unbiased shear estimators. For every galaxy we derive a shape measurement error and utilize this quantity to extract the intrinsic shape noise of the galaxy sample. Interestingly, our results indicate that intrinsic shape noise varies little with size, magnitude, or redshift. Representing a number density of 66 galaxies per arcmin2, the final COSMOS weak-lensing catalog contains 3.9 × 105 galaxies with accurate shape measurements. The properties of the COSMOS weak-lensing catalog described throughout this paper will provide key input numbers for the preparation and design of next-generation wide field space missions.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/2163f929d60db6012183c07c475b73572f118642

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Citations in the corpus

A WEAK LENSING STUDY OF X-RAY GROUPS IN THE COSMOS SURVEY: FORM AND EVOLUTION OF THE MASS–LUMINOSITY RELATION (2009, methodology): “In Leauthaud et al. (2007) and Rhodes et al. (2007), we remarked that the COSMOS ACS images are strongly affected by CTI.”
What does the Bullet Cluster tell us about Self-Interacting Dark Matter? (2016, background): “Leauthaud et al. (2007) found that for each galaxy σ int ∼0.26 across a wide range of sizes, magnitudes, and redshifts.”
Pixel-based correction for Charge Transfer Inefficiency in the Hubble Space Telescope Advanced Camera for Surveys (2009, methodology): “We use the algorithm by Rhodes, Refregier & Groth (2000), as implemented by Leauthaud et al. (2007) and Massey et al. (2007a), to recover the underlying galaxy ellipticities.”
Masses of Galaxy Clusters from Gravitational Lensing (2013, methodology): “In practice galaxies have an average intrinsic ellipticity of ∼ 0.25 per component (e.g., Hoekstra et al. 2000; Leauthaud et al. 2007), where the exact value depends somewhat on the galaxy type (e.g., van Uitert et al. 2012).”
Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology (2017, methodology): “Structure along the line of sight is visible in the higherresolution COSMOS redshifts but is not resolved by DES.”
COSMOS PHOTOMETRIC REDSHIFTS WITH 30-BANDS FOR 2-deg2 (2008, methodology): “Leauthaud et al. (2007) catalogued point-like sources in the COSMOS field using the peak surface brightness measured on the ACS images.”
UltraVISTA: a new ultra-deep near-infrared survey in COSMOS (2012, result): “To verify that our astrometric reference frame is consistent with COSMOS, we carried out a similar comparison with stars in the COSMOS ACS catalogue (Leauthaud et al. 2007); this is A156, page 7 of 11 shown in Fig.”
The First Release COSMOS Optical and Near-IR Data and Catalog (2007, methodology): “The resulting catalog is well matched in wavelength and depth to the HST-ACS catalog (Leauthaud et al. 2007) and optimally de-blends the ground based photometry.”
THE BULK OF THE BLACK HOLE GROWTH SINCE z ∼ 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER–AGN CONNECTION (2010, methodology): “Although the ACS survey of the COSMOS field is highly homogeneous, the exact depth achieved is dependent on the angle of the telescope with the Sun at the time of the observations (Leauthaud et al. 2007).”
THE COSMOS2015 CATALOG: EXPLORING THE 1 < z < 6 UNIVERSE WITH HALF A MILLION GALAXIES (2016, methodology): “Astrometric accuracy We compared the astrometric positions of bright, nonsaturated objects in COSMOS2015 with those in the COSMOS reference catalog from Leauthaud et al. (2007) and the publicly available i+-selected photometric catalog (footnote 4) described in Capak et al. (2007).”
DISSECTING PHOTOMETRIC REDSHIFT FOR ACTIVE GALACTIC NUCLEUS USING XMM- AND CHANDRA-COSMOS SAMPLES (2011, background): “Objects that appeared as point sources (as defined in Leauthaud et al. 2007) in deep COSMOS HST/ACS images (Koekemoer et al. 2007) and/or showed brightness fluctuations were grouped as QSOV (short for point-like or varying) and their photometry was corrected for variability, if necessary.”
The Hyper Suprime-Cam Software Pipeline (2017, methodology): “To produce more accurate star/galaxy classifications, we combine colors measured from CModel fluxes with extendedness via supervised machine learning, using the HST/ACS catalog of Leauthaud et al. (2007) to provide labels for the training set.”
THE CHANDRA COSMOS SURVEY. III. OPTICAL AND INFRARED IDENTIFICATION OF X-RAY POINT SOURCES (2012, methodology): “…AGN, for which the presence of a bright nuclear source can affect the determination of the concentration index (Gabor et al. 2009), we excluded from the sample sources classified as point-like from the ACS catalog (Leauthaud et al. 2007) and also sources classified as unobscured from their SED.”
The XMM-Newton Wide-Field Survey in the COSMOS Field. I. Survey Description (2006, background): “5m, which has also been covered almost completely by the HST ACS (1.67 deg2, see Leauthaud et al. 2007; Scoville et al. 2007).”
The DES Science Verification weak lensing shear catalogues (2015, background): “Most commonly, the shape measurements are made on coadded images of these multiple exposures (e.g. Wittman et al. 2000; Van Waerbeke et al. 2000; Heymans et al. 2005; Leauthaud et al. 2007; Fu et al. 2008).”
Mass and magnification maps for the Hubble Space Telescope Frontier Fields clusters: implications for high-redshift studies (2014, methodology): “Following a method developed for the analysis of data obtained for the COSMOS survey, and described in (Leauthaud et al. 2007, hereafter L07), the SEXTRACTOR photometry package (Bertin & Arnouts 1996) is used for the detection of the sources, using the ‘Hot–Cold’ method (Rix et al. 2004; L07).”
The Sloan Lens ACS Survey. IV. The Mass Density Profile of Early-Type Galaxies out to 100 Effective Radii (2007, methodology): “8 http://www.ifa.hawaii.edu/~kaiser/imcat/ The redshift distribution of sources is taken from the recently published COSMOS sample of faint galaxies detected in the ACS/F814W band (Leauthaud et al. 2007).”