CMB lensing bispectrum: Assessing analytical predictions against fullsky lensing simulations
Abstract
Cosmic microwave background (CMB) lensing is an integrated effect whose kernel is greater than half the peak value in the range 1 < z < 5 . Measuring this effect offers a powerful tool to probe the largescale structure of the Universe at high redshifts. With the increasing precision of ongoing CMB surveys, other statistics than the lensing power spectrum, in particular the lensing bispectrum, will be measured at high statistical significance. This will provide ways to improve the constraints on cosmological models and lift degeneracies. Following up on an earlier paper, we test analytical predictions of the CMB lensing bispectrum against fullsky lensing simulations, and we discuss their validity and limitation in detail. The treelevel prediction of perturbation theory agrees with the simulation only up to ℓ ∼ 200 , but the oneloop order allows capturing the simulation results up to ℓ ∼ 600 . We also show that analytical predictions based on fitting formulas for the matter bispectrum agree reasonably well with simulation results, although the precision of the agreement depends on the configurations and scales considered. For instance, the agreement is at the 10% level for the equilateral configuration at multipoles up to ℓ ∼ 2000 ,more »
 Authors:

 Univ. of Cambridge (United Kingdom). Dept. of Applied mathematics and Theoretical Physics; National Taiwan Univ., Taipei (Taiwan). Leung Center for Cosmology and Particle Astrophysics
 Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics; Univ. de Geneve (Switzerland). Dept. de Physique Theoretique
 Sorbonne Univ., Paris (France). Inst. d'Astrophysique de Paris
 Hirosaki Univ. (Japan). Faculty of Science and Technology
 Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics, Center for Gravitational Physics; Univ. of Tokyo (Japan). Inst. for Advanced Studies (UTIAS), Kavli Inst. for the Physics and Mathematics of the Universe
 Publication Date:
 Research Org.:
 Lawrence Berkeley National LaboratoryNational Energy Research Scientific Computing Center (NERSC)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1530436
 DOE Contract Number:
 AC0205CH11231
 Resource Type:
 Journal Article
 Journal Name:
 Physical Review D
 Additional Journal Information:
 Journal Volume: 99; Journal Issue: 6; Journal ID: ISSN 24700010
 Country of Publication:
 United States
 Language:
 English
Citation Formats
Namikawa, Toshiya, Bose, Benjamin, Bouchet, François R., Takahashi, Ryuichi, and Taruya, Atsushi. CMB lensing bispectrum: Assessing analytical predictions against fullsky lensing simulations. United States: N. p., 2019.
Web. doi:10.1103/PhysRevD.99.063511.
Namikawa, Toshiya, Bose, Benjamin, Bouchet, François R., Takahashi, Ryuichi, & Taruya, Atsushi. CMB lensing bispectrum: Assessing analytical predictions against fullsky lensing simulations. United States. doi:10.1103/PhysRevD.99.063511.
Namikawa, Toshiya, Bose, Benjamin, Bouchet, François R., Takahashi, Ryuichi, and Taruya, Atsushi. Fri .
"CMB lensing bispectrum: Assessing analytical predictions against fullsky lensing simulations". United States. doi:10.1103/PhysRevD.99.063511.
@article{osti_1530436,
title = {CMB lensing bispectrum: Assessing analytical predictions against fullsky lensing simulations},
author = {Namikawa, Toshiya and Bose, Benjamin and Bouchet, François R. and Takahashi, Ryuichi and Taruya, Atsushi},
abstractNote = {Cosmic microwave background (CMB) lensing is an integrated effect whose kernel is greater than half the peak value in the range 1 < z < 5 . Measuring this effect offers a powerful tool to probe the largescale structure of the Universe at high redshifts. With the increasing precision of ongoing CMB surveys, other statistics than the lensing power spectrum, in particular the lensing bispectrum, will be measured at high statistical significance. This will provide ways to improve the constraints on cosmological models and lift degeneracies. Following up on an earlier paper, we test analytical predictions of the CMB lensing bispectrum against fullsky lensing simulations, and we discuss their validity and limitation in detail. The treelevel prediction of perturbation theory agrees with the simulation only up to ℓ ∼ 200 , but the oneloop order allows capturing the simulation results up to ℓ ∼ 600 . We also show that analytical predictions based on fitting formulas for the matter bispectrum agree reasonably well with simulation results, although the precision of the agreement depends on the configurations and scales considered. For instance, the agreement is at the 10% level for the equilateral configuration at multipoles up to ℓ ∼ 2000 , but the difference in the squeezed limit increases to more than a factor of 2 at ℓ ∼ 2000 . This discrepancy appears to come from limitations in the fitting formula of the matter bispectrum. We also find that the analytical prediction for the postBorn correction to the bispectrum is in good agreement with the simulation. We conclude by discussing the bispectrum prediction in some theories of modified gravity.},
doi = {10.1103/PhysRevD.99.063511},
journal = {Physical Review D},
issn = {24700010},
number = 6,
volume = 99,
place = {United States},
year = {2019},
month = {3}
}