학술논문
CLASS Data Pipeline and Maps for 40 GHz Observations through 2022
Document Type
Working Paper
Author
Li, Yunyang; Eimer, Joseph; Osumi, Keisuke; Appel, John; Brewer, Michael; Ali, Aamir; Bennett, Charles; Bruno, Sarah Marie; Bustos, Ricardo; Chuss, David; Cleary, Joseph; Couto, Jullianna; Dahal, Sumit; Datta, Rahul; Denis, Kevin; Dunner, Rolando; Inostroza, Francisco Raul Espinoza; Essinger-Hileman, Thomas; Fluxa, Pedro; Harrington, Kathleen; Iuliano, Jeffrey; Karakla, John; Marriage, Tobias; Miller, Nathan; Novack, Sasha; Núñez, Carolina; Petroff, Matthew; Reeves, Rodrigo; Rostem, Karwan; Shi, Rui; Valle, Deniz; Watts, Duncan; Weiland, J.; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen
Source
Subject
Language
Abstract
The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background over 75\% of the sky from the Atacama Desert, Chile, at frequency bands centered near 40, 90, 150, and 220~GHz. This paper describes the CLASS data pipeline and maps for 40~GHz observations conducted from August 2016 to May 2022. We demonstrate how well the CLASS survey strategy, with rapid ($\sim10\,\mathrm{Hz}$) front-end modulation, recovers the large-scale Galactic polarization signal from the ground: the mapping transfer function recovers $\sim75$\% of $EE$, $BB$, and $VV$ power at $\ell=20$ and $\sim45$\% at $\ell=10$. We present linear and circular polarization maps over 75\% of the sky. Simulations based on the data imply the maps have a white noise level of $110\,\mathrm{\mu K\, arcmin}$ and correlated noise component rising at low-$\ell$ as $\ell^{-2.2}$. The transfer-function-corrected low-$\ell$ component is comparable to the white noise at the angular knee frequencies of $\ell\approx16$ (linear polarization) and $\ell\approx12$ (circular polarization). Finally, we present simulations of the level at which expected sources of systematic error bias the measurements, finding sub-percent bias for the $\Lambda\mathrm{CDM}$ $EE$ power spectra. Bias from $E$-to-$B$ leakage due to the data reduction pipeline and polarization angle uncertainty approaches the expected level for an $r=0.01$ $BB$ power spectrum. Improvements to the instrument calibration and the data pipeline will decrease this bias.
Comment: 29 pages, 17 figures; submitted to ApJ
Comment: 29 pages, 17 figures; submitted to ApJ