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Title: Lensing in the geodesic light-cone coordinates and its (exact) illustration to an off-center observer in Lemaȋtre-Tolman-Bondi models

We present in this paper a new application of the geodesic light-cone (GLC) gauge for weak lensing calculations. Using interesting properties of this gauge, we derive an exact expression of the amplification matrix—involving convergence, magnification and shear—and of the deformation matrix—involving the optical scalars. These expressions are simple and non-perturbative as long as no caustics are created on the past light-cone and are, by construction, free from the thin lens approximation. We apply these general expressions on the example of an Lemaȋtre-Tolman-Bondi (LTB) model with an off-center observer and obtain explicit forms for the lensing quantities as a direct consequence of the non-perturbative transformation between GLC and LTB coordinates. We show their evolution in redshift after a numerical integration, for underdense and overdense LTB models, and interpret their respective variations in the simple non-curvature case.
Authors:
 [1] ;  [2]
  1. Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)
  2. Glenco Group, Dipartimento di Fisica e Astronomia, Università di Bologna, viale B. Pichat 6/2 , 40127, Bologna (Italy)
Publication Date:
OSTI Identifier:
22382005
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 02; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLIFICATION; APPROXIMATIONS; COORDINATES; DEFORMATION; GALACTIC EVOLUTION; GRAVITATIONAL LENSES; LIGHT CONE; MATRICES; RED SHIFT; SHEAR; TRANSFORMATIONS; VARIATIONS