Theory and statistics of weak lensing from large-scale mass inhomogeneities |
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| Authors: | Marc Kamionkowski Arif Babul Catherine M Cress & Alexandre Refregier |
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| Institution: | Department of Physics, Columbia University, 538 West 120th Street, New York, NY 10027, USA,;Columbia Astrophysics Laboratory, 538 West 120th Street, New York, NY 10027, USA,;Department of Physics &38;Astronomy, University of Victoria, PO Box 3055, Victoria, BC V8W 3P6, Canada,;Department of Physics, New York University, 4 Washington Place, New York 10003, USA,;Department of Astronomy, Columbia University, 538 West 120th Street, New York, NY 10027, USA,;Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA |
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| Abstract: | 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 of these correlations and discuss calculations for the predicted signal. We consider the ellipticity correlation function, the mean-square ellipticity, the ellipticity power spectrum and a global maximum-likelihood analysis to isolate a weak-lensing signal from the data. Estimates for the sensitivity of a survey of a given area, surface density, and mean intrinsic source ellipticity are presented. We then apply our results to the FIRST radio-source survey. We predict an rms ellipticity of roughly 0.011 in 1 × 1 deg2 pixels and 0.018 in 20 × 20 arcmin2 pixels if the power spectrum is normalized to σ8 Ω0.53 = 0.6, as indicated by the cluster abundance. The signal is significantly larger in some models if the power spectrum is normalized instead to the COBE anisotropy. The uncertainty in the predictions from imprecise knowledge of the FIRST redshift distribution is about 25 per cent in the rms ellipticity. We show that FIRST should be able to make a statistically significant detection of a weak-lensing signal for cluster-abundance-normalized power spectra. |
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| Keywords: | cosmology: theory gravitational lensing large-scale structure of Universe |
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