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Detection of weak gravitational lensing by large-scale structure

Bacon, David J. and Refregier, Alexandre R. and Ellis, Richard S. (2000) Detection of weak gravitational lensing by large-scale structure. Monthly Notices of the Royal Astronomical Society, 318 (2). pp. 625-640. ISSN 0035-8711. doi:10.1046/j.1365-8711.2000.03851.x.

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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 mass power spectrum, as it is unaffected by poorly justified assumptions made concerning the biasing of the distribution. Our detection is based on an initial imaging study of 14 separated 8×16 arcmin² fields observed in good, homogeneous conditions with the prime focus EEV-CCD camera of the 4.2-m William Herschel Telescope. We detect an rms shear of 1.6 per cent in 8×8 arcmin² cells, with a significance of 3.4σ. We carefully justify this detection by quantifying various systematic effects and carrying out extensive simulations of the recovery of the shear signal from artificial images defined according to measured instrument characteristics. We also verify our detection by computing the cross-correlation between the shear in adjacent cells. Including (Gaussian) cosmic variance, we measure the shear variance to be (0.016)²±(0.012)²±(0.006)², where these 1σ errors correspond to statistical and systematic uncertainties, respectively. Our measurements are consistent with the predictions of cluster-normalized cold dark matter (CDM) models (within 1σ) but a Cosmic Background Explorer normalized standard cold dark matter model is ruled out at the 3.0σ level. For the currently favoured ΛCDM model (with Ωₘ=0.3), our measurement provides a normalization of the mass power spectrum of σ₈=1.5±0.5, fully consistent with that derived from cluster abundances. Our result demonstrates that ground-based telescopes can, with adequate care, be used to constrain the mass power spectrum on various scales. The present results are limited mainly by cosmic variance, which can be overcome in the near future with more observations.

Item Type:Article
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URLURL TypeDescription Paper
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2000 RAS. Received: 12 June 2000. Accepted: 12 June 2000. Published: 21 October 2000. We would like to thank Roger Blandford, Chris Benn, Andrew Firth, Mike Irwin, Andrew Liddle, Peter Schneider, Yannick Mellier, Roberto Maoli and Jason Rhodes for useful discussions. We are indebted to Nick Kaiser for providing us with the IMCAT software, and to Douglas Clowe for teaching us to use it. We thank Max Pettini for providing us with one of the WHT fields. We are also grateful to Ian Smail, the referee, for useful comments and suggestions. This work was performed within the European TMR lensing network. AR was supported by a TMR post-doctoral fellowship from this network, and by a Wolfson College Research Fellowship.
Funding AgencyGrant Number
European CommissionUNSPECIFIED
Wolfson CollegeUNSPECIFIED
Subject Keywords:cosmology: observations, gravitational lensing, large-scale structure of Universe
Issue or Number:2
Record Number:CaltechAUTHORS:20200526-104631415
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Official Citation:David J. Bacon, Alexandre R. Refregier, Richard S. Ellis, Detection of weak gravitational lensing by large-scale structure, Monthly Notices of the Royal Astronomical Society, Volume 318, Issue 2, October 2000, Pages 625–640,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103447
Deposited By: Rebecca Minjarez
Deposited On:27 May 2020 21:24
Last Modified:16 Nov 2021 18:21

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