Theory and statistics of weak lensing from largescale mass inhomogeneities
Abstract
Weak lensing by largescale 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 meansquare ellipticity, the ellipticity power spectrum and a global maximumlikelihood analysis to isolate a weaklensing 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 radiosource survey. We predict an rms ellipticity of roughly 0.011 in 1x1 deg^2 pixels and 0.018 in 20x20 arcmin^2 pixels if the power spectrum is normalized to sigma_8Omega^0.53=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 weaklensing signal for clusterabundancenormalized power spectra.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 December 1998
 DOI:
 10.1046/j.13658711.1998.02054.x
 arXiv:
 arXiv:astroph/9712030
 Bibcode:
 1998MNRAS.301.1064K
 Keywords:

 COSMOLOGY: THEORY;
 GRAVITATIONAL LENSING;
 LARGESCALE STRUCTURE OF UNIVERSE;
 Astrophysics
 EPrint:
 10 pages, 4 figures