2006ApJ...645....1D -
Astrophys. J., 645, 1-16 (2006/July-1)
Testing a new analytic model for gravitational lensing probabilities.
DAS S. and OSTRIKER J.P.
Abstract (from CDS):
We study gravitational lensing with a multiple lens plane approach, proposing a simple analytical model for the probability density function (pdf) of the dark matter convergence, κ, for the different lens planes in a given cosmology as a function of redshift and smoothing angle, θ. The model is fixed solely by the variance of κ, which in turn is fixed by the amplitude of the power spectrum, σ8. We test the pdf against a high-resolution tree particle-mesh simulation and find that it is far superior to the Gaussian or the lognormal, especially for small values of θ≪1' and at large values of κ relevant to strong lensing. With this model, we predict the probabilities of strong lensing by a single plane or by multiple planes. We find that for θ∼10'', a single plane accounts for almost all (∼98%) of the strong-lensing cases for source redshift unity. However, for a more typical source redshift of 4, about 12% of the strong-lensing cases will result from the contribution of a secondary clump of matter along the line of sight, introducing a systematic error in the determination of the surface density of clusters, typically overestimating it by about 2%-5%. We also find that matter inhomogeneities introduce a dispersion in the value of the angular diameter distance about its cosmological mean. The probable error relative to the mean increases with redshift to a value of about 8% for z≃6 and θ∼10''.
Abstract Copyright:
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Journal keyword(s):
Cosmology: Theory - Cosmology: Gravitational Lensing - Cosmology: Large-Scale Structure of Universe - Methods: Analytical
Simbad objects:
2
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