Statistical distribution of gravitational-lensing excursion angles: winding ways to us from the deep Universe |
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| Authors: | Takashi Hamana Matthias Bartelmann Naoki Yoshida Christoph Pfrommer |
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| Institution: | National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan;ITA, Universität Heidelberg, Tiergartenstr. 15, D–69121 Heidelberg, Germany;Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602, Japan;Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D–85748 Garching, Germany |
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| Abstract: | We investigate statistical distributions of differences in gravitational-lensing deflections between two light rays, the so-called lensing excursion angles. A probability distribution function of the lensing excursion angles, which plays a key role in estimates of lensing effects on angular clustering of objects (such as galaxies, quasi-stellar objects and also the cosmic microwave background temperature map), is known to consist of two components: a Gaussian core and an exponential tail. We use numerical gravitational-lensing experiments in a ΛCDM cosmology for quantifying these two components. We especially focus on the physical processes responsible for generating these two components. We develop a simple empirical model for the exponential tail which allows us to explore its origin. We find that the tail is generated by the coherent lensing scatter by massive haloes with M > 1014 h −1 M⊙ at z < 1 and that its exponential shape arises due to the exponential cut-off of the halo mass function at that mass range. On scales larger than 1 arcmin, the tail does not have a practical influence on the lensing effects on the angular clustering. Our model predicts that the coherent scatter may have non-negligible effects on angular clustering at subarcminute scales. |
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| Keywords: | gravitational lensing cosmology: theory dark matter large-scale structure of Universe |
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