CMB lensing reconstruction biases from masking extragalactic sources

Abstract

Observed Cosmic Microwave Background (CMB) maps are contaminated by foregrounds, some of which are usually masked to perform cosmological analyses. If masks are correlated to the lensing signal, such as those removing extragalactic emissions located in matter overdensities, measurements over the unmasked sky may give biased estimates. We quantify the impact of these mask-induced biases for the reconstructed CMB lensing auto- and cross-correlation power spectra with external matter tracers. We show that they arise both from changes in the lensing power, and via modifications to the reconstruction power spectrum corrections, $N_L^{(0)}$, $N_L^{(1)}$ and $N_L^{(3/2)}$). For direct masking of the CMB lensing field, we derive simple analytic models of the masking effect and show that it is potentially large. We show that mask-induced biases are significantly reduced by optimal filtering of the CMB maps in the lensing reconstruction. We test the resulting lensing power spectrum biases on numerical simulations, masking radio sources, and peaks of thermal Sunyaev-Zeldovich (tSZ) and cosmic infrared background (CIB) emission. For the lensing auto spectrum, masking biases can only be measured with a statistical significance $\lesssim 3\sigma$ for future data sets. The same applies to the cross-correlation power spectra between CMB lensing and tSZ and CIB even though biases are larger (up to ~30%). We find that masking tSZ-selected galaxy clusters leads to the largest mask biases, potentially detectable with high significance. We find that the calibration of cluster masses using CMB lensing, in particular for objects at $z\lesssim 0.6$, might be significantly affected by mask biases for near-future observations if the lensing signal recovered inside the mask holes is used without further corrections. Conversely, mass calibration of high redshift objects will still deliver unbiased results.

30 pages, 22 figures

References in corpus (10)

• CMB-S4 Science Case, Reference Design, and Project Plan
• Detection of Gravitational Lensing in the Cosmic Microwave Background
• CMB temperature lensing power reconstruction
• Demonstration of cosmic microwave background delensing using the cosmic infrared background
• Fundamental Physics from Future Weak-Lensing Calibrated Sunyaev-Zel'dovich Galaxy Cluster Counts
• CMB Lensing Beyond the Power Spectrum: Cosmological Constraints from the One-Point PDF and Peak Counts
• Constraining Cluster Virialization Mechanism and Cosmology using Thermal-SZ-selected clusters from Future CMB Surveys
• Investigating Cluster Astrophysics and Cosmology with Cross-Correlation of the Thermal Sunyaev-Zel'dovich Effect and Weak Lensing
• Improved estimation of cluster mass profiles from the cosmic microwave background
• Lensed CMB power spectrum biases from masking extragalactic sources

Cited by in corpus (11)

• Cosmology From CMB Lensing and Delensed EE Power Spectra Using 2019-2020 SPT-3G Polarization Data
• A Measurement of Gravitational Lensing of the Cosmic Microwave Background Using SPT-3G 2018 Data
• BICEP / Keck XVII: Line of Sight Distortion Analysis: Estimates of Gravitational Lensing, Anisotropic Cosmic Birefringence, Patchy Reionization, and Systematic Errors
• Simulated catalogs and maps of radio galaxies at millimeter wavelengths in Websky
• Optimal Estimation of the Binned Mask-Free Power Spectrum, Bispectrum, and Trispectrum on the Full Sky: Scalar Edition
• Constraining the galaxy-halo connection of infrared-selected unWISE galaxies with galaxy clustering and galaxy-CMB lensing power spectra
• Lensed CMB power spectrum biases from masking extragalactic sources
• Selecting samples of galaxies with fewer Fingers-of-God
• Accurate estimation of angular power spectra for maps with correlated masks
• The Atacama Cosmology Telescope: Mitigating the impact of extragalactic foregrounds for the DR6 CMB lensing analysis
• LiteBIRD science goals and forecasts: improved full-sky reconstruction of the gravitational lensing potential through the combination of Planck and LiteBIRD data