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

Abstract

We perform a complete study of the gravitational lensing effect beyond the Born approximation on the Cosmic Microwave Background (CMB) anisotropies using a multiple-lens raytracing technique through cosmological N-body simulations of the DEMNUni suite. The impact of second-order effects accounting for the non-linear evolution of large-scale structures is evaluated propagating for the first time the full CMB lensing jacobian together with the light rays trajectories. We carefully investigate the robustness of our approach against several numerical effects in the raytracing procedure and in the N-body simulation itself, and find no evidence of large contaminations. We discuss the impact of beyond-Born corrections on lensed CMB observables, and compare our results with recent analytical predictions that appeared in the literature, finding a good agreement, and extend these results to smaller angular scales. We measure the gravitationally-induced CMB polarization rotation that appears in the geodesic equation at second order, and compare this result with the latest analytical predictions. We then present the detection prospect of beyond-Born effects with the future CMB-S4 experiment. We show that corrections to the temperature power spectrum can be measured only if a good control of the extragalactic foregrounds is achieved. Conversely, the beyond-Born corrections on E and B-modesmore » power spectra will be much more difficult to detect.« less

Authors:
 [1];  [2];  [3]
  1. Univ. Paris-Sud, Orsay (France). Inst. d'Astrophysique Spatiale, CNRS; SISSA, Triste (Italy); Sezione di Triste, Triste (Italy). INFN
  2. Astronomical Observatory of the Autonomous Region of the Aosta Valley, Nus (Italy); Osservatorio Astrofisico di Torino, Pino Torinese (Italy). INAF; Osservatorio Astrofisica di Torino, Pino Torinese (Italy). INAF
  3. Univ. delgi Studi di Milano, Milano (Italy). Dipartmento di Fisica; Osservatorio Astronomico di Brera, Milano (Italy). INAF; Sezione di Milano, Milano (Italy). INFN
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1523616
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2018; Journal Issue: 02; Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English

Citation Formats

Fabbian, Giulio, Calabrese, Matteo, and Carbone, Carmelita. CMB weak-lensing beyond the Born approximation: a numerical approach. United States: N. p., 2018. Web. doi:10.1088/1475-7516/2018/02/050.
Fabbian, Giulio, Calabrese, Matteo, & Carbone, Carmelita. CMB weak-lensing beyond the Born approximation: a numerical approach. United States. doi:10.1088/1475-7516/2018/02/050.
Fabbian, Giulio, Calabrese, Matteo, and Carbone, Carmelita. Thu . "CMB weak-lensing beyond the Born approximation: a numerical approach". United States. doi:10.1088/1475-7516/2018/02/050. https://www.osti.gov/servlets/purl/1523616.
@article{osti_1523616,
title = {CMB weak-lensing beyond the Born approximation: a numerical approach},
author = {Fabbian, Giulio and Calabrese, Matteo and Carbone, Carmelita},
abstractNote = {We perform a complete study of the gravitational lensing effect beyond the Born approximation on the Cosmic Microwave Background (CMB) anisotropies using a multiple-lens raytracing technique through cosmological N-body simulations of the DEMNUni suite. The impact of second-order effects accounting for the non-linear evolution of large-scale structures is evaluated propagating for the first time the full CMB lensing jacobian together with the light rays trajectories. We carefully investigate the robustness of our approach against several numerical effects in the raytracing procedure and in the N-body simulation itself, and find no evidence of large contaminations. We discuss the impact of beyond-Born corrections on lensed CMB observables, and compare our results with recent analytical predictions that appeared in the literature, finding a good agreement, and extend these results to smaller angular scales. We measure the gravitationally-induced CMB polarization rotation that appears in the geodesic equation at second order, and compare this result with the latest analytical predictions. We then present the detection prospect of beyond-Born effects with the future CMB-S4 experiment. We show that corrections to the temperature power spectrum can be measured only if a good control of the extragalactic foregrounds is achieved. Conversely, the beyond-Born corrections on E and B-modes power spectra will be much more difficult to detect.},
doi = {10.1088/1475-7516/2018/02/050},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 02,
volume = 2018,
place = {United States},
year = {2018},
month = {2}
}

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