Detection of weak gravitational lensing by large-scale structure

By D. Bacon, Alexandre Refregier, Richard Ellis IoA, Cambridge, Caltech. 2000

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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.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/549d25149dcbe34c8643fa26f8c053f4aef4fb8e

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Citations in the corpus

Evidence of the accelerated expansion of the Universe from weak lensing tomography with COSMOS (2009, background): “Since its first detections by Bacon et al. (2000); Kaiser et al. (2000); Van Waerbeke et al. (2000) and Wittman et al. (2000), substantial progress has been made with the measurement of this cosmological weak lensing eff ct, which is also called cosmic shear.”
Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample (2010, background): “…decade, cosmic shear, the weak gravitational lensing effect by the large-scale structure of the Universe, has evolved from its first detections (Bacon et al. 2000; Kaiser et al. 2000; van Waerbeke et al. 2000; Wittman et al. 2000) into a wellestablished and regularly used cosmological probe…”
Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements (2007, background): “The first detections of cosmic shear made in 2000 (Bacon et al. 2000; Kaiser et al. 2000; Van Waerbeke et al. 2000; Wittman et al. 2000) demonstrated its value as a cosmological tool.”
Testing tidal-torque theory: I. spin amplitude and direction (2001, background): “A shear signal, interpreted as a result of gravitational lensing due to the large-scale distribution of matter, has been detected by several groups (Bacon et al. 2000; Kaiser et al. 2000; van Waerbeke et al. 2000, 2001; Wittman et al. 2000).”
Numerical simulations of the dark universe: State of the art and the next decade (2012, background): “The shear of galaxies has been detected statistically in many surveys [222–228] and has been used to place constraints on cosmological parameters [229–231].”
Gravitational lensing (2010, background): “The breakthrough came soon thereafter, when several different groups almost simultaneously reported the measurement of the cosmic shear correlation function [11, 306, 487, 507].”
First Cosmic Shear Results from the Canada-France-Hawaii Telescope Wide Synoptic Legacy Survey (2005, background): “The first detections, reported only a few years ago (Bacon et al. 2000; Kaiser et al. 2000; van Waerbeke et al. 2000; Wittman et al. 2000), were based on relatively small areas (a few deg2 at most).”
CFHTLenS: Improving the quality of photometric redshifts with precision photometry (2011, background): “Furthermore, the WL effect of the large scale structure (LSS) of the Universe, called cosmic shear (van Waerbeke et al. 2000; Kaiser et al. 2000; Bacon et al. 2000; Wittman et al. 2000; Semboloni et al. 2006; Hoekstra et al. 2006; Hetterscheidt et al. 2007; Schrabback et al. 2007, 2010; Massey et…”
Observational probes of cosmic acceleration (2012, background): “Cosmic shear was finally detected in 2000 by several groups (Wittman et al., 2000; Bacon et al., 2000; Van Waerbeke et al., 2000), and in deeper but narrower data from HST (Rhodes et al., 2001; Refregier et al., 2002).”