Special Astrophysics Seminar

CLASS: Large Angular Scale cosmology from the ground

Ivan Padilla

Johns Hopkins

CLASS is an array of four microwave polarimeters targeting large angular scales of the CMB. Precise measurements of the largest scales (2 < ell < 200) will provide constraints on the reionization optical depth, and on the tensor-to-scalar ratio that parametrizes the amplitude of primordial gravitational waves, a key prediction of the inflationary paradigm. CLASS leverages a front-end fast polarization modulator at 10 Hz to access the largest scales, and the four frequency bands at 40, 90, 150, and 220 GHz straddle the foreground minimum to disentangle galactic emission from the primordial signal. I will describe the telescope and select aspects of the first year of observations made with the 40 GHz instrument.