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UBC Theses and Dissertations

Probe the universe with PIXIE experiment and tSZ-lensing cross-correlation Yan, Ziang


The polarization of Cosmic Microwave Background can help us probe the early universe. The polarization pattern can be classified into E-mode and B- mode. The B-mode polarization is a smoking gun of cosmological inflation. PIXIE is an in-proposal space telescope observing CMB polarization. It is extremely powerful to extract CMB polarization signal from foreground contamination. The second chapter of this thesis summarizes my work on optimizing the optical system of PIXIE. I run a Monte-Carlo Markov Chain for the instrument parameters to maximize the value ”Good” which judges the behavior of the instrument. For the optimized instrument, with all kinds of noises from inside instrument and wrong polarization taken into account, good rays from the sky make up of 15.27% of all the rays received by the detector. The instrument has a 1.1° top-hat beam response. The third chapter summarizes my work on studying the potential con- tamination in the reconstructed y map by doing cross-correlation between tSZ signal and weak lensing. The weak lensing data is the convergence map from the Red Sequence Cluster Lensing Survey. I reconstruct the tSZ map with a Needlet Internal Linear Combination method with 6 HFI sky maps made by Planck satellite. The reconstructed cross correlation is consistent with Planck NILC SZ map. I take Cosmic Infrared Background (CIB) and galactic dust as two potential source of contamination in the reconstructed map. I find that κ × CIB contributes (5.8 ± 4.6)% in my reconstructed NILC y map for 500 < l < 2000 with 2.2σ significance. Dust residuals only change the error bar of the cross correlation signal. I find the best value for dust index is β_d = 1.57. I then introduce a piecewise power spectrum for the CIB and make a NILC CIB map to make a CIB-nulled NILC y map. κ × y signal from this y map differs by only ~0.08σ to the CIB-uncleaned y map.

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