Title: Optimizing foreground mitigation for CMB lensing with combined multifrequency and geometric methods

Abstract

Here, a key challenge for current and upcoming cosmic microwave background lensing measurements is their sensitivity to biases from extragalactic foregrounds, such as Sunyaev-Zel'dovich signals or cosmic infrared background emission. Several methods have been developed to mitigate these lensing foreground biases, dividing broadly into multifrequency cleaning approaches and modifications to the estimator geometry, but how to optimally combine these methods has not yet been explored in detail. In this paper, we examine which combination of lensing foreground mitigation strategies is best able to reduce the impact of foreground contamination for a Simons Observatory-like experiment while preserving maximal signal-to-noise. Although the optimal combination obtained depends on whether bias reduction or variance reduction is prioritized and on whether polarization data is used, generally, we find that combinations involving both geometric (profile hardening, source hardening, or shear) and multifrequency (symmetric cleaning) methods perform best. For lensing power spectrum measurements from temperature (polarization and temperature), our combined estimator methods are able to reduce the bias below σ/4 or 0.3% (0.1%), a factor of 16 (30) lower than the standard quadratic estimator bias, at a modest signal-to-noise cost of only 18% (12%). In contrast, single-method foreground-mitigation approaches struggle to reduce the bias to a negligiblemore » level below σ/2 without incurring a large noise penalty. For upcoming and current experiments, our combined methods therefore represent a promising approach for making lensing measurements with negligible foreground bias.« less

Authors:

Darwish, Omar  ^[1];

• Search DOE PAGES for author "Darwish, Omar"
• Search DOE PAGES for ORCID "0000-0003-2946-1866"

Sherwin, Blake D. ^[1]; Sailer, Noah ^[2]; Schaan, Emmanuel  ^[3];

• Search DOE PAGES for author "Schaan, Emmanuel"
• Search DOE PAGES for ORCID "0000-0002-4619-8927"

Ferraro, Simone ^[3]

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+ Show Author Affiliations

1. Univ. of Cambridge (United Kingdom)
2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

Publication Date:

Tue Feb 14 00:00:00 EST 2023

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)

OSTI Identifier:

1967355

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review. D.

Additional Journal Information:

Journal Volume: 107; Journal Issue: 4; Journal ID: ISSN 2470-0010

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Cosmic microwave background; Astrophysical & cosmological simulations