Résumé / Abstract Journal-club_Univers

Journal-club Univers / Journal-club Universe

« CMB weak-lensing beyond the Born approximation: a numerical approach »

Giulio Fabbian
Postdoc - Inst. Astroph. Spatiale (IAS), Univ. Paris-Sud XI (Orsay, France)

The upcoming and future generation of CMB experiments will observe the effect of gravitational lensing on CMB anisotropies with unprecedented sensitivity. Being able to model this effect with the required level of precision will be mandatory in order to exploit this observable for cosmological applications. In this scenario, it will be particularly important to assess the impact of the assumptions usually made to describe this phenomenon, like the gaussianity of the matter distribution and the single deflection (Born) approximation. I will discuss results of recent numerical works that tested both these aspects using a multiple lens raytracing techniques through cosmological N-body simulations. I will present the first analysis of the full set of components of the CMB lensing jacobian at first order and beyond the Born approximation as well as the impact of beyond Born corrections on the lensed CMB observables. I will then show a detailed comparison of the numerical results with recent analytical predictions that appeared in the literature and discuss the detection prospect of beyond Born effects with the future CMB-S4 experiment.
mardi 21 février 2017 - 11:15
Salle 281, Institut d'Astrophysique
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