Quantifying Bias due to non-Gaussian Foregrounds in an Optimal Reconstruction of CMB Lensing and Temperature Power Spectra

2025/02/28 by M. Doohan, M. Millea, Doohan, M. +13 · 1 voice · 1 citation
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #astro-ph.CO

paper · pdf · doi:10.48550/arxiv.2502.20801

arxiv published 2025/02/28 · arxiv updated 2025/07/24

Abstract

We estimate the magnitude of the bias due to non-Gaussian extragalactic foregrounds on the optimal reconstruction of the cosmic microwave background (CMB) lensing potential and temperature power spectra. The reconstruction is performed using a Bayesian inference method known as the marginal unbiased score expansion (MUSE). We apply MUSE to a minimum variance combination of multifrequency maps drawn from the Agora publicly available simulations of the lensed CMB and correlated extragalactic foreground emission. Taking noise levels appropriate to the SPT-3G D1 release, we find non-Gaussian foregrounds may bias the MUSE reconstruction of the lensing potential amplitude at the level of (0.7± 0.3) σ when using modes up to ℓ_max=3500. We do not detect a statistically significant bias, finding a value of (-0.4± 0.3) σ, when restricted to lower angular multipoles, ℓ_max=3000. This work is a first step toward understanding the impact of extragalactic foregrounds on optimal reconstructions of CMB temperature and lensing potential power spectra.

Cited by

• Non-Gaussianity in SMICA

Discussions

• This type of field-level modelling might be very important for reconstructing the gravitational lensing of the CMB (see e.g. arxiv.org/abs/2502.20801), which is itself important, among other things, f [bsky, 3 points, 1 comments]

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