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Gravitational lensing with three-dimensional ray tracing

Authors

  • M. Killedar,

    Corresponding author
    1. Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006, Australia
    2. Dipartimento di Fisica dell’Università di Trieste, Sezione di Astronomia, Via Tiepolo 11, I-34131 Trieste, Italy
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  • P. D. Lasky,

    Corresponding author
    1. Theoretical Astrophysics, Eberhard Karls University of Tübingen, Tübingen 72076, Germany
    2. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
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  • G. F. Lewis,

    1. Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006, Australia
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  • C. J. Fluke

    1. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
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  • Research undertaken as part of the Commonwealth Cosmology Initiative (CCI: http://www.thecci.org), an international collaboration supported by the Australian Research Council (ARC).

E-mail: killedar@oats.inaf.it (MK); lasky@tat.physik.uni-tuebingen.de (PDL)

ABSTRACT

High-redshift sources suffer from magnification or demagnification due to weak gravitational lensing by large-scale structure. One consequence of this is that the distance–redshift relation, in wide use for cosmological tests, suffers lensing-induced scatter which can be quantified by the magnification probability distribution. Predicting this distribution generally requires a method for ray tracing through cosmological N-body simulations. However, standard methods tend to apply the multiple-thin-lens approximation. In an effort to quantify the accuracy of these methods, we develop an innovative code that performs ray tracing without the use of this approximation. The efficiency and accuracy of this computationally challenging approach can be improved by careful choices of numerical parameters; therefore, the results are analysed for the behaviour of the ray-tracing code in the vicinity of Schwarzschild and Navarro–Frenk–White lenses. Preliminary comparisons are drawn with the multiple-lens-plane ray-bundle method in the context of cosmological mass distributions for a source redshift of zs= 0.5.

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