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Joint cosmic shear measurements with the Keck and William Herschel Telescopes

Bacon, David J. and Massey, Richard J. and Refregier, Alexandre R. and Ellis, Richard S. (2003) Joint cosmic shear measurements with the Keck and William Herschel Telescopes. Monthly Notices of the Royal Astronomical Society, 344 (3). pp. 673-685. ISSN 0035-8711. doi:10.1046/j.1365-8711.2003.06877.x.

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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 survey carried out with the Echelle Spectrograph and Imager on the Keck II telescope. This covers a total of 0.6 square degrees in 173 fields probing independent lines of sight, hence minimizing the impact of sample variance. We also extend our measurements of cosmic shear with the William Herschel Telescope (Bacon, Refregier & Ellis 2000) to a survey area of 1 square degree. The joint measurements with two independent telescopes allow us to assess the impact of instrument-specific systematics, one of the major difficulties in cosmic shear measurements. For both surveys, we account for effects such as smearing by the point spread function and shearing due to telescope optics carefully. We find negligible residuals in both cases and recover mutually consistent cosmic shear signals, significant at the 5.1σ level. We present a simple method to compute the statistical error in the shear correlation function, including non-Gaussian sample variance and the covariance between different angular bins. We measure shear correlation functions for all fields and use these to ascertain the amplitude of the matter power spectrum, finding σ₈(Ω_m/0.3)^(0.68) = 0.97 ± 0.13 with 0.14 < Ω_m < 0.65 in a Λ cold dark matter (ΛCDM) model with Γ= 0.21. These 68 per cent confidence level uncertainties include sample variance, statistical noise, redshift uncertainty and the error in the shear measurement method. The results from our two independent surveys are both consistent with measurements of cosmic shear from other groups. We discuss how our results compare with current normalization from cluster abundance.

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URLURL TypeDescription Paper
Massey, Richard J.0000-0002-6085-3780
Additional Information:© 2003 RAS. Received: 12 May 2003. Accepted: 19 May 2003. Published: 21 September 2003. We are indebted to Nick Kaiser for providing us with the IMCAT software and to Douglas Clowe for advice on its use. We thank Mike Bolte and staff at the Keck Observatory for their assistance in implementing the new wide-field filter on the Echellette Spectrographic Imager. We thank Sarah Bridle, Tzu-Ching Chang and Jason Rhodes for useful discussions. We also thank Mark Sullivan for his help in securing some of the Keck data and Max Pettini for providing us with one of the WHT fields. DJB was supported by a PPARC postdoctoral fellowship. AR was supported by a TMR postdoctoral fellowship from the EEC Lensing Network, and by a Wolfson College Research Fellowship.
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Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Wolfson CollegeUNSPECIFIED
Subject Keywords:gravitational lensing, cosmology: observations, large-scale structure of Universe
Issue or Number:3
Record Number:CaltechAUTHORS:20200608-110444337
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Official Citation:David J. Bacon, Richard J. Massey, Alexandre R. Refregier, Richard S. Ellis, Joint cosmic shear measurements with the Keck and William Herschel Telescopes, Monthly Notices of the Royal Astronomical Society, Volume 344, Issue 3, September 2003, Pages 673–685,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103749
Deposited By: Rebecca Minjarez
Deposited On:08 Jun 2020 21:34
Last Modified:16 Nov 2021 18:24

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