Relativistic weak lensing from a fully non-linear cosmological density field

Journal Article · Tue Sep 01 00:00:00 EDT 2015 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2015/09/021· OSTI ID:22525386

Thomas, D. B. ^[1]; Bruni, M.

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1. Department of Physics, University of Cyprus, Aglantzia, Nicosia, 2109 Cyprus (Cyprus)

In this paper we examine cosmological weak lensing on non-linear scales and show that there are Newtonian and relativistic contributions and that the latter can also be extracted from standard Newtonian simulations. We use the post-Friedmann formalism, a post-Newtonian type framework for cosmology, to derive the full weak-lensing deflection angle valid on non-linear scales for any metric theory of gravity. We show that the only contributing term that is quadratic in the first order deflection is the expected Born correction and lens-lens coupling term. We use this deflection angle to analyse the vector and tensor contributions to the E- and B- mode cosmic shear power spectra. In our approach, once the gravitational theory has been specified, the metric components are related to the matter content in a well-defined manner. Specifying General Relativity, we write down a complete set of equations for a GR+ΛCDM universe for computing all of the possible lensing terms from Newtonian N-body simulations. We illustrate this with the vector potential and show that, in a GR+ΛCDM universe, its contribution to the E-mode is negligible with respect to that of the conventional Newtonian scalar potential, even on non-linear scales. Thus, under the standard assumption that Newtonian N-body simulations give a good approximation of the matter dynamics, we show that the standard ray tracing approach gives a good description for a ΛCDM cosmology.

• OSTI ID: 22525386
• Journal Information: Journal of Cosmology and Astroparticle Physics, Vol. 2015, Issue 09; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
APPROXIMATIONS
COMPUTERIZED SIMULATION
CORRECTIONS
COSMOLOGICAL CONSTANT
COSMOLOGICAL MODELS
COSMOLOGY
COUPLING
DENSITY
GENERAL RELATIVITY THEORY
GRAVITATION
GRAVITATIONAL LENSES
METRICS
NONLINEAR PROBLEMS
POTENTIALS
RELATIVISTIC RANGE
SCALARS
SHEAR
UNIVERSE
VECTORS