Weak lensing forecasts for dark energy, neutrinos and initial conditions (2009)
Debono, Ivan, Rassat, Anais, Refregier, Alexandre, Amara, Adam, Kitching, Thomas
Weak gravitational lensing provides a sensitive probe of cosmological parameters by measuring the mass distribution and the geometry of the low redshift universe. We show how an all-sky weak lensing...
Berge, Joel, Amara, Adam, Refregier, Alexandre
We compare the efficiency of weak lensing-selected galaxy clusters counts and of the weak lensing bispectrum at capturing non-Gaussian features in the dark matter distribution. We use the halo model...
Results of the GREAT08 Challenge: An image analysis competition for cosmological lensing (2009)
Bridle, Sarah, Balan, Sreekumar T., Bethge, Matthias, Gentile, Marc, Harmeling, Stefan, Heymans, Catherine, ...
We present the results of the GREAT08 Challenge, a blind analysis challenge to infer weak gravitational lensing shear distortions from images. The primary goal was to stimulate new ideas by...
Cloud Cosmology : Building the Web Interface for iCosmo (2009)
Kitching, Thomas, Amara, Adam, Rassat, Anais, Refregier, Alexandre
Astronomy and cosmology have embraced the internet. We routinely and successfully use the internet as a repository for sharing code, publications and information, and as a computational resource....
iCosmo: an Interactive Cosmology Package (2008)
Refregier, Alexandre, Amara, Adam, Kitching, Thomas, Rassat, Anais
iCosmo is a software package to perform interactive cosmological calculations for the low redshift universe. The computation of distance measures, the matter power spectrum, and the growth factor is...
Deconstructing Baryon Acoustic Oscillations: A Comparison of Methods (2008)
Rassat, Anais, Amara, Adam, Amendola, Luca, Castander, Francisco J., Kitching, Thomas, Kunz, Martin, ...
The Baryon Acoustic Oscillations (BAOs) or baryon wiggles which are present in the galaxy power spectrum at scales 100-150Mpc/h are powerful features with which to constrain cosmology. The potential...
Subaru Weak Lensing survey -- II: Multi-object Spectroscopy and Cluster Masses (2008)
Hamana, Takashi, Miyazaki, Satoshi, Kashikawa, Nobunari, Ellis, Richard S., Massey, Richard J., Refregier, Alexandre, ...
We present the first results of a MOS campaign to follow up cluster candidates located via weak lensing. Our main goals are to search for spatial concentrations of galaxies that are plausible optical...
Summary of the DUNE Mission Concept (2008)
Refregier, Alexandre, Douspis, Marian, Collaboration, The DUNE
The Dark UNiverse Explorer (DUNE) is a wide-field imaging mission concept whose primary goal is the study of dark energy and dark matter with unprecedented precision. To this end, DUNE is optimised...
The focal plane instrumentation for the DUNE mission (2008)
Booth, Jeff, Cropper, Mark, Eisenhauer, Frank, Refregier, Alexandre, Collaboration, The DUNE
DUNE (Dark Universe Explorer) is a proposed mission to measure parameters of dark energy using weak gravitational lensing The particular challenges of both optical and infrared focal planes and the...
Full-Sky Weak Lensing Simulation with 70 Billion Particles (2008)
Teyssier, Romain, Pires, Sandrine, Prunet, Simon, Aubert, Dominique, Pichon, Christophe, Amara, Adam, ...
We have performed a 70 billion dark-matter particles N-body simulation in a 2 $h^{-1}$ Gpc periodic box, using the concordance, cosmological model as favored by the latest WMAP3 results. We have...
First catalog of strong lens candidates in the COSMOS field (2008)
Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...
We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 deg^2 Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or strongly...
The Dark UNiverse Explorer (DUNE): Proposal to ESA's Cosmic Vision (2008)
Refregier, Alexandre, Collaboration, The DUNE
The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter with unprecedented precision. For this purpose, DUNE is optimised for the...
First catalog of strong lens candidates in the COSMOS field (2008)
Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...
We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 square degree Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or...
Handbook for the GREAT08 Challenge: An image analysis competition for cosmological lensing (2008)
Bridle, Sarah, Shawe-Taylor, John, Amara, Adam, Applegate, Douglas, Balan, Sreekumar T., Berge, Joel, ...
The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. The shapes of distant galaxies can be used...
The focal plane instrumentation for the DUNE mission (2008)
Booth, Jeff, Cropper, Mark, Eisenhauer, Frank, Refregier, Alexandre, DUNE Collaboration
First catalog of strong lens candidates in the COSMOS field (2008)
Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...
Erratum: "First catalog of strong lens candidates in the COSMOS field" (ApJS, 176, 19 [2008]) (2008)
Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...
First catalog of strong lens candidates in the COSMOS field (2008)
Faure, Cecile, Kneib, Jean-Paul, Covone, Giovanni, Tasca, Lidia, Leauthaud, Alexie, Capak, Peter, ...
We present the first catalog of 67 strong galaxy-galaxy lens candidates discovered in the 1.64 deg2 Hubble Space Telescope COSMOS survey. Twenty of these systems display multiple images or strongly...
Theory and Statistics of Weak Lensing from Large-Scale Mass Inhomogeneities (2007)
Marc Kamionkowski Arif, Catherine M. Cress, Alexandre Refregier
Weak lensing by large-scale mass inhomogeneities in the Universe induces correlations in the observed ellipticities of distant sources. We first review the harmonic analysis and statistics required...
Effect of Correlated Noise on Source Shape Parameters and Weak Lensing Measurements (2007)
Alexandre Refregier, Scott T. Brown
The measurement of shape parameters of sources in astronomical images is usually performed by assuming that the underlying noise is uncorrelated. Spatial noise correlation is however present in...
Systematic Bias in Cosmic Shear: Beyond the Fisher Matrix (2007)
Amara, Adam, Refregier, Alexandre
We describe a method for computing the biases that systematic signals introduce in parameter estimation using a simple extension of the Fisher matrix formalism. This allows us to calculate the offset...
Weak gravitational shear and flexion with polar shapelets (2007)
Massey, Richard, Rowe, Barnaby, Refregier, Alexandre, Bacon, David J., Bergé, Joel
We derive expressions, in terms of 'polar shapelets', for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive...
A Subaru Weak Lensing Survey I: Cluster Candidates and Spectroscopic Verification (2007)
Miyazaki, Satoshi, Hamana, Takashi, Ellis, Richard S., Kashikawa, Nobunari, Massey, Richard J., Taylor, James, ...
We present the results of an ongoing weak lensing survey conducted with the Subaru telescope whose initial goal is to locate and study the distribution of shear-selected structures or halos. Using a...
COSMOS: 3D weak lensing and the growth of structure (2007)
Massey, Richard, Rhodes, Jason, Leauthaud, Alexie, Capak, Peter, Ellis, Richard, Koekemoer, Anton, ...
We present a three dimensional cosmic shear analysis of the Hubble Space Telescope COSMOS survey, the largest ever optical imaging program performed in space. We have measured the shapes of galaxies...
Rhodes, Jason D., Massey, Richard, Albert, Justin, Collins, Nicholas, Ellis, Richard S., Heymans, Catherine, ...
(abridged) We examine the spatial and temporal stability of the HST ACS Wide Field Camera (WFC) point spread function (PSF) using the two square degree COSMOS survey. We show that stochastic aliasing...
Dark matter maps reveal cosmic scaffolding (2007)
Massey, Richard, Rhodes, Jason, Ellis, Richard, Scoville, Nick, Leauthaud, Alexie, Finoguenov, Alexis, ...
Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious "dark matter" component, which does not...
Rhodes, Jason D., Massey, Richard, Albert, Justin, Collins, Nicholas, Ellis, Richard S., Heymans, Catherine, ...
(abridged) We examine the spatial and temporal stability of the HST ACS Wide Field Camera (WFC) point spread function (PSF) using the two square degree COSMOS survey. We show that stochastic aliasing...
Dark matter maps reveal cosmic scaffolding (2007)
Massey, Richard, Rhodes, Jason, Ellis, Richard, Scoville, Nick, Leauthaud, Alexie, Finoguenov, Alexis, ...
Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious "dark matter" component, which does not...
COSMOS: 3D weak lensing and the growth of structure (2007)
Massey, Richard, Rhodes, Jason, Leauthaud, Alexie, Capak, Peter, Ellis, Richard, Koekemoer, Anton, ...
We present a three dimensional cosmic shear analysis of the Hubble Space Telescope COSMOS survey, the largest ever optical imaging program performed in space. We have measured the shapes of galaxies...
Dark matter maps reveal cosmic scaffolding (2007)
Massey, Richard, Rhodes, Jason, Ellis, Richard, Scoville, Nick, Leauthaud, Alexie, Finoguenov, Alexis, ...
Optimal Surveys for Weak Lensing Tomography (2006)
Amara, Adam, Refregier, Alexandre
Weak lensing surveys provide a powerful probe of dark energy through the measurement of the mass distribution of the local Universe. A number of ground-based and space-based surveys are being planned...
Weak gravitational shear and flexion with polar shapelets (2006)
Massey, Richard, Rowe, Barnaby, Refregier, Alexandre, Bacon, David J., Berge, Joel
We derive expressions, in terms of "polar shapelets", for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive...
The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses (2006)
Massey, Richard, Heymans, Catherine, Berge, Joel, Bernstein, Gary, Bridle, Sarah, Clowe, Douglas, ...
The Shear TEsting Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak lensing measurement, in preparation for the next generation of wide-field surveys. We...
The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations (2006)
Heymans, Catherine, Van Waerbeke, Ludovic, Bacon, David, Berge, Joel, Bernstein, Gary, Bertin, Emmanuel, ...
The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In...
Massey, Richard, Refregier, Alexandre
The shapelets method for image analysis is based upon the decomposition of localized objects into a series of orthogonal components with convenient mathematical properties. We extend the 'Cartesian...
The Shear TEsting Programme 1: Weak lensing analysis of simulated ground-based observations (2005)
Heymans, Catherine, Van Waerbeke, Ludovic, Bacon, David, Berge, Joel, Bernstein, Gary, Bertin, Emmanuel, ...
The Shear TEsting Programme, STEP, is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In...
Weak Lensing Mass Reconstruction using Wavelets (2005)
Starck, Jean-Luc, Pires, Sandrine, Refregier, Alexandre
This paper presents a new method for the reconstruction of weak lensing mass maps. It uses the multiscale entropy concept, which is based on wavelets, and the False Discovery Rate which allows us to...
Weak Lensing by Large-Scale Structure with the FIRST Radio Survey (2004)
Chang, Tzu-Ching, Refregier, Alexandre, Helfand, David J.
We present the first measurement of weak lensing by large-scale structure on 1-4 degree scales based on the FIRST Radio Survey, a quarter-sky, 20-cm survey produced with the NRAO Very Large Array...
Shapelets "multiple multipole" shear measurement methods (2004)
Massey, Richard, Refregier, Alexandre, Bacon, David
The measurement of weak gravitational lensing is currently limited to a precision of ~10% by instabilities in galaxy shape measurement techniques and uncertainties in their calibration. The potential...
An Enlarged Cosmic Shear Survey with the William Herschel Telescope (2004)
Massey, Richard, Refregier, Alexandre, Bacon, David J., Ellis, Richard, Brown, Michael L.
We report the results of a cosmic shear survey using the 4.2m William Herschel Telescope on La Palma, to a depth of R=25.8 (z~0.8), over 4 square degrees. The shear correlation functions are measured...
Probing Dark Matter and Dark Energy with Space-Based Weak Lensing (2004)
Massey, Richard, Refregier, Alexandre, Rhodes, Jason
Weak lensing provides a direct measure of the distribution of mass in the universe, and is therefore a uniquely powerful probe of dark matter. Weak lensing can also be used to measure the twin...
The XMM-LSS survey : Survey design and first results* (2004)
Pierre, Marguerite, Valtchanov, Ivan, Altieri, Bruno, Andreon, Stefano, Bolzonella, Micol, Bremer, Malcolm, ...
Measurement of Cosmic Shear with the Space Telescope Imaging Spectrograph (2003)
Rhodes, Jason, Refregier, Alexandre, Collins, Nicholas R., Gardner, Jonathan P., Groth, Edward J., Hill, Robert S.
Weak lensing by large-scale structure allows a direct measure of the dark matter distribution. We have used parallel images taken with the Space Telescope Imaging Spectrograph (STIS) on the Hubble...
Weak Gravitational Lensing by Large-Scale Structure (2003)
Weak gravitational lensing provides a unique method to map directly the distribution of dark matter in the universe and to measure cosmological parameters. This cosmic-shear technique is based on the...
Weak Lensing from Space I: Instrumentation and Survey Strategy (2003)
Rhodes, Jason, Refregier, Alexandre, Massey, Richard, Collaboration, The SNAP
A wide field space-based imaging telescope is necessary to fully exploit the technique of observing dark matter via weak gravitational lensing. This first paper in a three part series outlines the...
Weak Lensing from Space II: Dark Matter Mapping (2003)
Massey, Richard, Rhodes, Jason, Refregier, Alexandre, Albert, Justin, Bacon, David, Bernstein, Gary, ...
We study the accuracy with which weak lensing measurements could be made from a future space-based survey, predicting the subsequent precisions of 3-dimensional dark matter maps, projected...
Weak Lensing from Space III: Cosmological Parameters (2003)
Refregier, Alexandre, Massey, Richard, Rhodes, Jason, Ellis, Richard, Albert, Justin, Bacon, David, ...
Weak gravitational lensing provides a unique method to directly map the dark matter in the universe and measure cosmological parameters. Current weak lensing surveys are limited by the atmospheric...
Image Simulation with Shapelets (2003)
Massey, Richard, Refregier, Alexandre, Conselice, Christopher J., Bacon, David J.
We present a method to simulate deep sky images, including realistic galaxy morphologies and telescope characteristics. To achieve a wide diversity of simulated galaxy morphologies, we first use the...
Joint Cosmic Shear Measurements with the Keck and William Herschel Telescopes (2002)
Bacon, David, Massey, Richard, Refregier, Alexandre, Ellis, Richard
The recent measurements of weak lensing by large-scale structure present significant new opportunities for studies of the matter distribution in the universe. Here, we present a new cosmic shear...
Shapelets: A New Method to Measure Galaxy Shapes (2002)
Refregier, Alexandre, Chang, Tzu-Ching, Bacon, David
We present a new approach to measure the shapes of galaxies, a fundamental task in observational astronomy. This approach is based on the decomposition of a galaxy image into a series of orthogonal...
Cosmic Shear with Keck: Systematic Effects (2001)
Massey, Richard, Bacon, David, Refregier, Alexandre, Ellis, Richard
Cosmic shear probes the distribution of dark matter via gravitational lensing of distant, background galaxies. We describe our cosmic shear survey consisting of deep blank fields observed with the...
Cosmology with Galaxy Clusters in the XMM Large-Scale Structure Survey (2001)
Refregier, Alexandre, Valtchanov, Ivan, Pierre, Marguerite
The upcoming XMM Large Scale Structure Survey (XMM-LSS) will ultimately provide a unique mapping of the distribution of X-ray sources in a contiguous 64 sq. deg. region. In particular, it will...
Shape Reconstruction and Weak Lensing Measurement with Interferometers: A Shapelet Approach (2001)
Chang, Tzu-Ching, Refregier, Alexandre
We present a new approach for image reconstruction and weak lensing measurements with interferometers. Based on the shapelet formalism presented in Refregier (2001), object images are decomposed into...
Shapelets: I. A Method for Image Analysis (2001)
We present a new method for the analysis of images, a fundamental task in observational astronomy. It is based on the linear decomposition of each object in the image into a series of localised basis...
Shapelets: II. A Method for Weak Lensing Measurements (2001)
Refregier, Alexandre, Bacon, David
Weak gravitational lensing provides a unique method to directly measure the distribution of mass in the universe. Because the distortions induced by lensing in the shape of background galaxies are...
CMB anisotropy from spatial correlations of clusters of galaxies (2000)
Komatsu, Eiichiro, Kitayama, Tetsu, Refregier, Alexandre, Spergel, David N., Pen, Ue-Li
The SZ effect from clusters of galaxies is a dominant source of secondary CMB anisotropy in the low-redshift universe. We present analytic predictions for the CMB power spectrum from massive halos...
Numerical and Analytical Predictions for the Large-Scale Sunyaev-Zel'dovich Effect (2000)
Refregier, Alexandre, Teyssier, Romain
The hot gas embedded in the large-scale structures in the Universe produces secondary fluctuations in the Cosmic Microwave Background (CMB). Because it is proportional to the gas pressure integrated...
Detection of Cosmic Shear with the William Herschel Telescope (2000)
Bacon, David, Refregier, Alexandre, Ellis, Richard
Gravitational lensing by large-scale structure induces weak coherent alignments in the shapes of background galaxies. Here we present evidence for the detection of this `cosmic shear' at the 3.4...
Numerical Simulations of Weak Lensing Measurements (2000)
Bacon, David, Refregier, Alexandre, Clowe, Douglas, Ellis, Richard
(Abridged) Weak gravitational lensing induces distortions on the images of background galaxies, and thus provides a direct measure of mass fluctuations in the universe. Since the distortions induced...
Intrinsic Correlation of Galaxy Shapes: Implications for Weak Lensing Measurements (2000)
Heavens, Alan, Refregier, Alexandre, Heymans, Catherine
Weak gravitational lensing is now established as a powerful method to measure mass fluctuations in the universe. It relies on the measurement of small coherent distortions of the images of background...
Infrared observations of gravitational lensing in Abell 2219 with CIRSI (2000)
Gray, Meghan E., Ellis, Richard S., Refregier, Alexandre, Bezecourt, Jocelyn, McMahon, Richard G., Beckett, Martin G., ...
We present the first detection of a gravitational depletion signal at near-infrared wavelengths, based on deep panoramic images of the cluster Abell 2219 (z=0.22) taken with the Cambridge Infrared...
Natarajan, Priyamvada, Refregier, Alexandre
We propose a new technique to directly measure the shapes of dark matter halos of galaxies using weak gravitational lensing. Extending the standard galaxy-galaxy lensing method, we show that the...
Detection of Weak Gravitational Lensing by Large-scale Structure (2000)
Bacon, David, Refregier, Alexandre, Ellis, Richard
We report a detection of the coherent distortion of faint galaxies arising from gravitational lensing by foreground structures. This ``cosmic shear'' is potentially the most direct measure of the...
Weak Lensing Measurements: A Revisited Method and Application to HST Images (1999)
Rhodes, Jason, Refregier, Alexandre, Groth, Ed
The weak distortions produced by gravitational lensing in the images of background galaxies provide a method to measure directly the distribution of mass in the universe. However this technique...
Theory and Statistics of Weak Lensing from Large-Scale Mass Inhomogeneities (1997)
Kamionkowski, Marc, Babul, Arif, Cress, Catherine M., Refregier, Alexandre
Weak lensing by large-scale mass inhomogeneities in the Universe induces correlations in the observed ellipticities of distant sources. We first review the harmonic analysis and statistics required...
Discrete-source backgrounds in cosmology (1997)
Cosmological backgrounds can be decomposed into a component originating from diffuse emission, and one produced by a collection of discrete sources. The object of the present thesis is the study of...
Discrete-source backgrounds in cosmology / (1997)
Thesis (Ph. D.)--Columbia University, 1997.
Discrete-source backgrounds in cosmology--[microform] /--Alexandre Refregier. (1997)
Department: Physics.
Gravitational Lensing of the X-Ray Background by Clusters of Galaxies (1996)
Refregier, Alexandre, Loeb, Abraham
Gravitational lensing by clusters of galaxies affects the cosmic X-ray background (XRB) by altering the observed density and flux distribution of background X-ray sources. At faint detection flux...
Effect of Gravitational Lensing on Measurements of the Sunyaev-Zel'dovich Effect (1996)
Loeb, Abraham, Refregier, Alexandre
The Sunyaev-Zel'dovich (SZ) effect of a cluster of galaxies is usually measured after background radio sources are removed from the cluster field. Gravitational lensing by the cluster potential leads...
Probing Cluster Potentials through Gravitational Lensing of Background X-Ray Sources (1995)
Refregier, Alexandre, Loeb, Abraham
We examine the gravitational lensing effect of a foreground galaxy cluster on the number count statistics of background X-ray sources. The lensing produces a deficit in the number of resolved sources...