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Relativistic weak lensing from a fully non-linear cosmological density field
- Publication Year :
- 2014
-
Abstract
- 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$+\Lambda$CDM 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$+\Lambda$CDM 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 $\Lambda$CDM cosmology.<br />Comment: Updated to match version published in JCAP
Details
- Database :
- arXiv
- Publication Type :
- Report
- Accession number :
- edsarx.1403.4947
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1088/1475-7516/2015/09/021