Browsing by Author "Nunez, Carolina"

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    CLASS Angular Power Spectra and Map-component Analysis for 40 GHz Observations through 2022
    (2024) Eimer, Joseph R.; Li, Yuyang; Brewer, Michael K.; Shi, Rui; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Bruno, Sarah Marie; Bustos, Ricardo; Chuss, David T.; Cleary, Joseph; Dahal, Sumit; Datta, Rahul; Denes Couto, Jullianna; Denis, Kevin L.; Dunner, Rolando; Essinger-Hileman, Thomas; Fluxa, Pedro; Hubmayer, Johannes; Harrington, Kathleen; Iuliano, Jeffrey; Karakla, John; Marriage, Tobias A.; Nunez, Carolina; Parker, Lucas; Petroff, Matthew A.; Reeves, Rodrigo A.; Rostem, Karwan; Valle, Deniz A. N.; Watts, Duncan J.; Weiland, Janet L.; Wollack, Edward J.; Xu, Zhilei; Zeng, Lingzhen
    Measurement of the largest angular scale (l < 30) features of the cosmic microwave background (CMB) polarization is a powerful way to constrain the optical depth to reionization and search for the signature of inflation through the detection of primordial B-modes. We present an analysis of maps covering 73.6% of the sky made from the 40 GHz channel of the Cosmology Large Angular Scale Surveyor (CLASS) from 2016 August to 2022 May. Taking advantage of the measurement stability enabled by front-end polarization modulation and excellent conditions from the Atacama Desert, we show this channel achieves higher sensitivity than the analogous frequencies from satellite measurements in the range 10 < l < 100. Simulations show the CLASS linear (circular) polarization maps have a white noise level of 125(130)mu Karcmin . We measure the Galaxy-masked EE and BB spectra of diffuse synchrotron radiation and compare to space-based measurements at similar frequencies. In combination with external data, we expand measurements of the spatial variations of the synchrotron spectral energy density (SED) to include new sky regions and measure the diffuse SED in the harmonic domain. We place a new upper limit on a background of circular polarization in the range 5 < l < 125 with the first bin showing D- l < 0.023 mu K-CMB(2) at 95% confidence. These results establish a new standard for recovery of the largest-scale CMB polarization from the ground and signal exciting possibilities when the higher sensitivity and higher-frequency CLASS channels are included in the analysis.
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    CLASS Data Pipeline and Maps for 40 GHz Observations through 2022
    (2023) Li, Yunyang; Eimer, Joseph R.; Osumi, Keisuke; Appel, John W.; Brewer, Michael K.; Ali, Aamir; Bennett, Charles L.; Bruno, Sarah Marie; Bustos, Ricardo; Chuss, David T.; Cleary, Joseph; Couto, Jullianna Denes; Dahal, Sumit; Datta, Rahul; Denis, Kevin L.; Dunner, Rolando; Espinoza, Francisco; Essinger-Hileman, Thomas; Rojas, Pedro Fluxa; Harrington, Kathleen; Iuliano, Jeffrey; Karakla, John; Marriage, Tobias A.; Miller, Nathan J.; Novack, Sasha; Nunez, Carolina; Petroff, Matthew A.; Reeves, Rodrigo A.; Rostem, Karwan; Shi, Rui; Valle, Deniz A. N.; Watts, Duncan J.; Weiland, Janet L.; Wollack, Edward J.; Xu, Zhilei; Zeng, Lingzhen; CLASS Collaboration
    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 2016 August to 2022 May. We demonstrate how well the CLASS survey strategy, with rapid (similar to 10 Hz) front-end modulation, recovers the large-scale Galactic polarization signal from the ground: the mapping transfer function recovers similar to 67% (85%) of EE and BB (VV) power at l = 20 and similar to 35% (47%) at l = 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 mu Karcmin and correlated noise component rising at low-l as l -2.4. The transfer-function-corrected low-l component is comparable to the white noise at the angular knee frequencies of l approximate to 18 (linear polarization) and l approximate to 12 (circular polarization). Finally, we present simulations of the level at which expected sources of systematic error bias the measurements, finding subpercent bias for the Lambda cold dark matter 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.