**AAS Meeting #193 - Austin, Texas, January 1999**

*Session 117. Gravitational Lensing*

Oral, Saturday, January 9, 1999, 2:00-3:30pm, Ballroom B
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## [117.02] Cosmological Parameters from Gravitational Lensing by Large-Scale Structure

*B. Jain (JHU), U. Seljak (CfA), S. White (MPA)*

Large-scale structure in the universe shears and magnifies
the images of distant galaxies. Measurement of this weak
lensing effect on randomly selected, degree sized fields
promises to be a powerful tool for mapping large-scale
structure in the universe. We have developed analytical and
numerical methods for linking theoretical predictions of
shear statistics with observational data. Ray tracing
simulations, coupled with an ensemble of high resolution
N-body simulations of the dark matter distribution, have
been used to generate maps of the shear and magnification
fields that span the range of scales accessible to weak
lensing observations. These maps have been used to compute
the power spectrum, spatial moments, and the probability
distribution function of the shear and magnification. Sample
sizes required to measure the power spectrum from noisy data
have been estimated. The skewness of the probability
distribution function can be used to estimate Omega. Our
results suggest that with a total survey area of order 10
square degrees the shear power spectrum can be accurately
measured on scales of 1-10 Mpc , and Omega determined to
within about 0.1. Comparison of the shear field with galaxy
surveys will provide a direct measure of the biasing of
galaxies.

The author(s) of this abstract have provided an email address
for comments about the abstract:
bjain@pha.jhu.edu

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