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News&Com

COMING UP NEXT

Wednesday, May 17th, 2017 - Department of Physics, University of Milan - 3:30pm

Post-Born effects and all-sky mock catalogs for CMB-lensing by Matteo Calabrese

I will present a complete study of the gravitational lensing effect beyond-the-Born-approximation on the Cosmic Microwave Background (CMB) anisotropies. The study exploits ray-tracing techniques to follow the photons’ path from the last scattering surface, as they travel throughout an all-sky lightcone built by compressing the matter distribution of N-Body numerical simulations into a set of lensing shells. The impact of second-order effects accounts for the non-linear evolution of large-scale structures, and it is evaluated by propagating the full CMB lensing Jacobian together with the light rays trajectory. I will show the robustness of the approach against several numerical effects both in the ray-tracing procedure and in the N-body simulation, finding no evidence of large contaminations of the signal. I will show the impact of post-Born CMB observables, comparing the results with recent analytical corrections on lensed predictions, and discussing the detection prospect of post-Born effects in future CMB experiments. Finally, I will apply the simulation pipeline to model the cross-correlation between CMB lensing and large scale structure tracers, by means of all-sky, galaxy mock catalogues. The simulated signal can enable a thorough investigation of structure formation over cosmic time, thus mimicking possible measurements from the forthcoming ESA-mission Euclid.

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