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Register a new userWeak Lensing by Large-Scale Structure: A Dark Matter Halo Approach
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Asantha Cooray
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Weak gravitational lensing observations probe the spectrum and evolution of density fluctuations and the cosmological parameters which govern them but are currently limited to small fields and subject to selection biases. We show how the expected signal from large-scale structure arises from the contributions from and correlations between individual halos. We determine the convergence power spectrum as a function of the maximum halo mass and so provide the means to interpret results from surveys that lack high mass halos either through selection criteria or small fields. Since shot noise from rare massive halos is mainly responsible for the sample variance below 10, our method should aid our ability to extract cosmological information from small fields.
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Selected results on estimating cosmological parameters from simulated weak lensing data with noise are presented. Numerical simulations of ray tracing through N-body simulations have been used to generate shear and convergence maps due to lensing by large-scale structure. Noise due to the intrinsic ellipticities of a finite number of galaxies is added. In this contribution we present our main results on estimation of the power spectrum and density parameter Omega from weak lensing data on several degree sized fields. We also show that there are striking morphological differences in the weak lensing maps of clusters of galaxies formed in models with different values of Omega.
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