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Improving CMB non-Gaussianity estimators using tracers of local structure

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journal contribution
posted on 2023-06-08, 00:59 authored by James M G Mead, Antony LewisAntony Lewis, Lindsay King
Local non-Gaussianity causes correlations between large-scale perturbation modes and the small-scale power. The large-scale CMB signal has contributions from the integrated Sachs-Wolfe (ISW) effect, which does not correlate with the small-scale power. If this ISW contribution can be removed, the sensitivity to local non-Gaussianity is improved. Gravitational lensing and galaxy counts can be used to trace the ISW contribution; in particular, we show that the CMB lensing potential is highly correlated with the ISW signal. We construct a nearly optimal estimator for the local non-Gaussianity parameter fNL and investigate to what extent we can use this to decrease the variance on fNL. We show that the variance can be decreased by up to 20% at Planck sensitivity using galaxy counts. CMB lensing is a good bias-independent ISW tracer for future more sensitive observations, though the fractional decrease in variance is small if good polarization data are also available.

History

Publication status

  • Published

File Version

  • Published version

Journal

Physical Review D

ISSN

1550-7998

Publisher

American Physical Society

Issue

2

Volume

83

Page range

023507

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

First Open Access (FOA) Date

2016-03-22

First Compliant Deposit (FCD) Date

2016-08-17

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