Constraints on the Polarized Dust and the Cosmic Microwave Background Using BICEP / Keck Array Series of Telescopes

Citation

Kefeli, Sinan (2023) Constraints on the Polarized Dust and the Cosmic Microwave Background Using BICEP / Keck Array Series of Telescopes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/7a55-p606. https://resolver.caltech.edu/CaltechTHESIS:05142023-053312973

Abstract

BK18 data consists of all the data taken by the Bicep2, Keck Array, and Bicep3 CMB polarization experiments, as well as publicly available WMAP and Planck maps. The Q/U maps reach depths of 2.8, 2.8 and 8.8 µK_CMB arcmin at 95, 150, and 220 GHz respectively over an effective area of ~ 600 square degrees at 95 GHz and ~ 400 square degrees at 150 and 220 GHz. The likelihood analysis yields r < 0.036 at 95% confidence, with unbiased simulations yielding σ(r)=0.009. The multi-component model that is used in the likelihood analysis consists of lensed-ΛCDM, tensor modes, and polarize dust and synchrotron components. Foreground model consists of thirteen parameters, some of which are estimated in the likelihood analysis with priors derived from larger regions of sky from WMAP and Planck: amplitude, spectral index, and spatial index for dust and sync, as well as their spatial correlation; dust frequency decorrelation and tensor-to-scalar-ratio. Spectral index for dust emission no longer requires a prior taken from measurements on other regions of the sky.

In the BK papers, EE spectra are not used to derive the model, however the spectra agree well with the assumption that EE/BB = 2 for dust. In this thesis we expand on this assumption, sharing the results for the EE/BB estimate for dust when this is a free parameter in the likelihood calculation. We use the map-based and spectral-based band difference approaches to include E-modes in the likelihood analysis. In the BK papers, dust parameters are assumed to be constant over the sky. We will go over the likelihood work on the spatial constraints for the dust spectral index to examine the validity of this assumption.

Thesis Files