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Full covariance of CMB and lensing reconstruction power spectra

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posted on 2023-06-09, 11:36 authored by Julien PelotonJulien Peloton, Marcel Schmittfull, Antony LewisAntony Lewis, Julien Carron, Oliver Zahn
CMB and lensing reconstruction power spectra are powerful probes of cosmology. However, they are correlated, since the CMB power spectra are lensed, and the lensing reconstruction is constructed using CMB multipoles. We perform a full analysis of the auto- and cross-covariances, including polarization power spectra and minimum-variance lensing estimators, and compare with simulations of idealized future CMBS4 observations. Covariances sourced by fluctuations in the unlensed CMB and instrumental noise can largely be removed by using a realization-dependent subtraction of lensing reconstruction noise, leaving a relatively simple covariance model that is dominated by lensing-induced terms and well described by a small number of principal components. The correlations between the CMB and lensing power spectra will be detectable at the level of ~5s for a CMB-S4 mission, and neglecting them could underestimate some parameter error bars by several tens of percent. However, we found that the inclusion of external priors or data sets to estimate parameter error bars can make the impact of the correlations almost negligible.

Funding

Astrophysics and Cosmology - Sussex Consolidated Grant; G1291; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/L000652/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Physical Review D

ISSN

2470-0010

Publisher

American Physical Society

Issue

4

Volume

95

Page range

043508-1

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-01-15

First Open Access (FOA) Date

2018-01-15

First Compliant Deposit (FCD) Date

2018-01-15

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