Impact of Galactic non-Gaussian foregrounds on CMB lensing measurements
Weak gravitational lensing of the cosmic microwave background (CMB) has been established as a robust and powerful observable for precision cosmology. However, the impact of Galactic foregrounds, which has been studied less extensively than many other potential systematics, could in principle pose a problem for CMB lensing measurements. These foregrounds are inherently non-Gaussian and hence might mimic the characteristic signal that lensing estimators are designed to measure. We present an analysis that quantifies the level of contamination from Galactic dust in lensing measurements, focusing particularly on measurements with the Atacama Cosmology Telescope and the Simons Observatory. We employ a whole suite of foreground models and study the contamination of lensing measurements with both individual frequency channels and multifrequency combinations. We test the sensitivity of different estimators to the level of foreground non-Gaussianity and the dependence on sky fraction and multipole range used. We find that Galactic foregrounds do not present a problem for the Atacama Cosmology Telescope experiment (the bias in the inferred CMB lensing power spectrum amplitude remains below <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>0.3</a:mn><a:mi>σ</a:mi></a:mrow></a:math>). For Simons Observatory, not all foreground models remain below this threshold. Although our results are conservative upper limits, they suggest that further work on characterizing dust biases and determining the impact of mitigation methods is well motivated, especially for the largest sky fractions.
Authors
- Frank J. Qu (ORCID: https://orcid.org/0000-0001-7805-1068)
- Carlos Hervías-Caimapo (ORCID: https://orcid.org/0000-0002-4765-3426)
- N. MacCrann (ORCID: https://orcid.org/0000-0002-8998-3909)
- Mathew S. Madhavacheril (ORCID: https://orcid.org/0000-0001-6740-5350)
- Neelima Sehgal (ORCID: https://orcid.org/0000-0002-9674-4527)
- Alexander van Engelen (ORCID: https://orcid.org/0000-0002-3495-158X)
- Omar Darwish (ORCID: https://orcid.org/0000-0003-2946-1866)
- Irene Abril-Cabezas (ORCID: https://orcid.org/0000-0003-3230-4589)
- J. Colin Hill (ORCID: https://orcid.org/0000-0002-9539-0835)
- Blake D. Sherwin (ORCID: https://orcid.org/0000-0002-4495-1356)
Institutions
- University of Geneva (CH)
- Pontificia Universidad Católica de Chile (CL)
- University of Cambridge (GB)
- California University of Pennsylvania (US)
- Kavli Institute for Particle Astrophysics and Cosmology (US)
- Arizona State University (US)
- Stony Brook University (US)
- Columbia University (US)
- Stanford University (US)
Publication Details
- Journal
- Physical review. D/Physical review. D.
- Published
- 2025-06-16
- DOI
- https://doi.org/10.1103/jhmr-mg6w
- Citations
- 2
- Primary Topic
- Cosmology and Gravitation Theories
- Type
- article
- Field-Weighted Citation Impact
- 2.31
Funders
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- Simons Foundation
- Dell EMC
- Department for Business, Energy and Industrial Strategy, UK Government
- UK Research and Innovation
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Agencia Nacional de Investigación y Desarrollo
- Horizon 2020 Framework Programme
- Engineering and Physical Sciences Research Council
- Science and Technology Facilities Council
- European Research Council
- Fondo Nacional de Desarrollo Científico y Tecnológico