Publication : t09/200

Full-sky lensing shear at second order

Bernardeau F. (CEA, IPhT (Institut de Physique Théorique), F-91191 Gif-sur-Yvette, France)
Bonvin C. (CEA, IPhT (Institut de Physique Théorique), F-91191 Gif-sur-Yvette, France)
Vernizzi F. (CEA, IPhT (Institut de Physique Théorique), F-91191 Gif-sur-Yvette, France)
We compute the reduced cosmic shear up to second order in the gravitational potential without relying on the small angle or thin-lens approximation. This is obtained by solving the Sachs equation which describes the deformation of the infinitesimal cross-section of light bundle in the optical limit, and maps galaxy intrinsic shapes into their angular images. The calculation is done in the Poisson gauge without a specific matter content, including vector and tensor perturbations generated at second order and taking account of the inhomogeneities of a fixed redshift source plane. Our final result is expressed in terms of spin-2 operators on the sphere and is valid on the full sky. Beside the well known lens-lens and Born corrections that dominate on small angular scales, we find new non-linear couplings. These are a purely general relativistic intrinsic contribution, a coupling between the gravitational potential at the source with the lens, couplings between the time delay with the lens, couplings between two photon deflections, as well as non-linear couplings due to the second-order vector and tensor components. The inhomogeneity in the redshift of the source induces a coupling between the photon redshift with the lens. All these corrections become important on large angular scales and should thus be included when computing higher-order observables such as the bispectrum, in full or partially full-sky surveys.
Année de publication : 2010
Revue : Phys. Rev. D 81 083002 (2010)
DOI : 10.1103/PhysRevD.81.083002
Preprint : arXiv:0911.2244
Lien :
PACS : 95.30.Sf, 98.65.Dx, 98.80.Es, 98.80.Jk
Langue : Anglais

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  • PhysRevD.81.083002.pdf
  • publi.pdf


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