Cosmology Large Angular Scale Surveyor (CLASS): Recent progress and the 40 GHz results - Yunyang Li (Johns Hopkins)

Tuesday 31 Oct 2023, 12:30 → 13:30 America/Los_Angeles

48/2-224 - Madrone (SLAC)

I will discuss the development and recent progress of the CLASS telescope (Cosmology Large Angular Scale Surveyor) with a highlight on its 40 GHz survey. CLASS is a four-frequency telescope array in the Atacama desert in northern Chile, observing the cosmic microwave background (CMB) polarization at 40, 90, and 150/220 GHz. By measuring the CMB E mode polarization on large angular scales (ell<30), CLASS will be able to constrain the optical depth toward the last scattering surface and improve upon the sum of the neutrino mass measurement. In this talk, I will focus on the data reduction pipeline development and the results from the 40 GHz maps. The data pipeline includes the demodulation of the signal from the novel variable delay polarization modulator, systematic issues mitigation, and map-making. We also present the 40 GHz polarization maps that cover 75\% of the sky from the ground, with signal recovery 75\% (45\%) at angular scales ell=20 (10). These maps show synchrotron power spectrum and frequency dependency consistent with the satellite measurements and with superior sensitivity in the range 10<ell<100. CLASS also places the tightest constraints on the astrophysical circular polarization background. This talk will conclude with an outlook on the future development of the CLASS experiment.

Join from PC, Mac, Linux, iOS or Android: https://stanford.zoom.us/j/98973156241?pwd=cEU5RFdlVXoyc0JTeTlDMkozKzQ5UT09

FPD_seminar_20231031_compressed.pdf

video1305542900.mp4