JCAP-1605.05662v2-Accepted.pdf (7.82 MB)
Impact of post-Born lensing on the CMB
journal contribution
posted on 2023-06-09, 04:42 authored by Geraint Pratten, Antony LewisAntony LewisLensing of the CMB is affected by post-Born lensing, producing corrections to the convergence power spectrum and introducing field rotation. We show numerically that the lensing convergence power spectrum is affected at the lesssim 0.2% level on accessible scales, and that this correction and the field rotation are negligible for observations with arcminute beam and noise levels gsim 1 µK arcmin. The field rotation generates ~ 2.5% of the total lensing B-mode polarization amplitude (0.2% in power on small scales), but has a blue spectrum on large scales, making it highly subdominant to the convergence B modes on scales where they are a source of confusion for the signal from primordial gravitational waves. Since the post-Born signal is non-linear, it also generates a bispectrum with the convergence. We show that the post-Born contributions to the bispectrum substantially change the shape predicted from large-scale structure non-linearities alone, and hence must be included to estimate the expected total signal and impact of bispectrum biases on CMB lensing reconstruction quadratic estimators and other observables. The field-rotation power spectrum only becomes potentially detectable for noise levels Lt 1 µK arcmin, but its bispectrum with the convergence may be observable at ~ 3s with Stage IV observations. Rotation-induced and convergence-induced B modes are slightly correlated by the bispectrum, and the bispectrum also produces additional contributions to the lensed BB power spectrum.
Funding
Precision cosmological parameters : CosmoPars; G1365; EUROPEAN UNION; 616170 ERC-2013-CoG
Astrophysics and Cosmology - Sussex Consolidated Grant; G1291; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/L000652/1
History
Publication status
- Published
File Version
- Accepted version
Journal
Journal of Cosmology and Astroparticle PhysicsISSN
1475-7516Publisher
IOP PublishingExternal DOI
Issue
8Volume
2016Page range
047-047Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Astronomy Centre Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2017-01-13First Open Access (FOA) Date
2017-08-23First Compliant Deposit (FCD) Date
2017-01-13Usage metrics
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