Measurements of tropospheric ice clouds with a ground-based CMB polarization experiment, POLARBEAR

Abstract

The polarization of the atmosphere has been a long-standing concern for ground-based experiments targeting cosmic microwave background (CMB) polarization. Ice crystals in upper tropospheric clouds scatter thermal radiation from the ground and produce a horizontally-polarized signal. We report the detailed analysis of the cloud signal using a ground-based CMB experiment, POLARBEAR, located at the Atacama desert in Chile and observing at 150 GHz. We observe horizontally-polarized temporal increases of low-frequency fluctuations ("polarized bursts," hereafter) of $\lesssim$0.1 K when clouds appear in a webcam monitoring the telescope and the sky. The hypothesis of no correlation between polarized bursts and clouds is rejected with $>$24$\sigma$ statistical significance using three years of data. We consider many other possibilities including instrumental and environmental effects, and find no other reasons other than clouds that can explain the data better. We also discuss the impact of the cloud polarization on future ground-based CMB polarization experiments.

arXiv comment14 pages, 12 figures, 1 table, Submitted to ApJ

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Cited by in corpus (12)

• Updated design of the CMB polarization experiment satellite LiteBIRD
• A Measurement of the Degree Scale CMB B-mode Angular Power Spectrum with POLARBEAR
• Improved upper limit on degree-scale CMB B-mode polarization power from the 670 square-degree POLARBEAR survey
• Two Year Cosmology Large Angular Scale Surveyor (CLASS) Observations: Long Timescale Stability Achieved with a Front-End Variable-delay Polarization Modulator at 40 GHz
• Two-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: A First Detection of Atmospheric Circular Polarization at Q Band
• The Atacama Cosmology Telescope: Modeling Bulk Atmospheric Motion
• Measurement and Modeling of Polarized Atmosphere at the South Pole with SPT-3G
• The Simons Observatory: Beam characterization for the Small Aperture Telescopes
• Study on the filters of atmospheric contamination in ground based CMB observation
• The Atacama Cosmology Telescope: Quantifying Atmospheric Emission above Cerro Toco
• A measurement of atmospheric circular polarization with POLARBEAR
• Testing magnetic interference between TES detectors and the telescope environment for future CMB satellite missions