Open Collections

Fatigoni, Sofia

University of British Columbia

The standard model of cosmology (ΛCDM ) is able to statistically describe the observable Universe with a small set of parameters that have been mea- sured to a percent level precision through observations of the Cosmic Mi- crowave Background (CMB) [Aghanim et al. 2020]. While this model shows a remarkable agreement with the data, it still can’t explain all the features we observe in the CMB. One of the biggest mysteries resides on the fact that CMB radiation sky is extremely uniform in temperature, despite that it was generated when the Universe was so young that just small patches of sky could be in causal contact. As an add on to the Standard Cosmological Model the theory of inflation [Guth 1981] was introduced, to solve this set of puzzles. One prediction from Inflation is the presence of a background of gravitational waves, in the primordial Universe, that would have produced a unique parity-odd pattern in the polarization of the CMB, also known as B-Modes. Until now no CMB experiment was able to find B-Modes. As B-modes are very low in signal (O(Bmodes) ∼ 10⁻⁷O(∆T )), finding them is one of the biggest challenges of Cosmology today and it requires an ex- tremely sensitive and low noise instrument, high level of systematics control and an accurate model for foregrounds subtraction. In this thesis I will go through the design of BICEP Array (BA), the latest multi frequency instru- ment part of the BICEP/Keck (BK) experiment, which is optimized for the search of B-Modes. I will show the instrument tuning and characterization process and explain the observation strategy. I will also explain the latest results from the BK data, show how these data allow a huge step forward in our understanding of inflation and what are the prospects in the search for B-Modes with BICEP Array. I will then show how, using a Water Vapour Radiometer located next to the telescope, I developed a new method for atmospheric noise subtraction that could allow us to recover a fraction of the low-frequency B-Modes power spectrum, which is otherwise lost during data processing.

Text

2023-03-09

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83910

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/