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Title: Lens covariance effects on likelihood analyses of CMB power spectra

Abstract

Non-Gaussian correlations induced in CMB power spectra by gravitational lensing needs to be included in likelihood analyses for future CMB experiments. We present a simple but accurate likelihood model which includes these correlations and use it for Markov Chain Monte Carlo parameter estimation from simulated lensed CMB maps in the context of ΛCDM and extensions which include the sum of neutrino masses or the dark energy equation of state w. If lensing-induced covariance is not taken into account for a CMB-S4 type experiment, the errors for one combination of parameters in each case would be underestimated by more then a factor of two and lower limits on w could be misestimated substantially. The frequency of falsely ruling out the true model or finding tension with other data sets would also substantially increase. Our analysis also enables a separation of lens and unlensed information from CMB power spectra, which provides for consistency tests of the model and, if combined with other such measurements, a nearly lens-sample-variance free test for systematics and new physics in the unlensed spectrum. This parameterization also leads to a simple effective likelihood that can be used to assist model building in case consistency tests of ΛCDM fail.

Authors:
 [1];  [1]
  1. Univ. of Chicago, IL (United States)
Publication Date:
Research Org.:
Univ. of Chicago, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1595668
Alternate Identifier(s):
OSTI ID: 1408932
Grant/Contract Number:  
SC0009924; FG02-13ER41958
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 10; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Motloch, Pavel, and Hu, Wayne. Lens covariance effects on likelihood analyses of CMB power spectra. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.103517.
Motloch, Pavel, & Hu, Wayne. Lens covariance effects on likelihood analyses of CMB power spectra. United States. doi:10.1103/PhysRevD.96.103517.
Motloch, Pavel, and Hu, Wayne. Wed . "Lens covariance effects on likelihood analyses of CMB power spectra". United States. doi:10.1103/PhysRevD.96.103517. https://www.osti.gov/servlets/purl/1595668.
@article{osti_1595668,
title = {Lens covariance effects on likelihood analyses of CMB power spectra},
author = {Motloch, Pavel and Hu, Wayne},
abstractNote = {Non-Gaussian correlations induced in CMB power spectra by gravitational lensing needs to be included in likelihood analyses for future CMB experiments. We present a simple but accurate likelihood model which includes these correlations and use it for Markov Chain Monte Carlo parameter estimation from simulated lensed CMB maps in the context of ΛCDM and extensions which include the sum of neutrino masses or the dark energy equation of state w. If lensing-induced covariance is not taken into account for a CMB-S4 type experiment, the errors for one combination of parameters in each case would be underestimated by more then a factor of two and lower limits on w could be misestimated substantially. The frequency of falsely ruling out the true model or finding tension with other data sets would also substantially increase. Our analysis also enables a separation of lens and unlensed information from CMB power spectra, which provides for consistency tests of the model and, if combined with other such measurements, a nearly lens-sample-variance free test for systematics and new physics in the unlensed spectrum. This parameterization also leads to a simple effective likelihood that can be used to assist model building in case consistency tests of ΛCDM fail.},
doi = {10.1103/PhysRevD.96.103517},
journal = {Physical Review D},
number = 10,
volume = 96,
place = {United States},
year = {2017},
month = {11}
}

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