UC San Diego

In this dissertation, we explore two aspects of the dark matter using cosmology. In Chapter 2, we study the interaction between axion, a famous dark matter candidate, and ordinary matter, through their trace left in the thermal history of the universe. We show that the axion- matter coupling can be constrained by the effective number of relativistic species, Neff, with next-generation CMB experiments. In Chapter 3, we study the distribution of matter before inflation, by conducting massive galaxy surveys of the large-scale structure of the universe. We show that the measurement of the primordial non-gaussianity of matter distribution can be significantly optimized by various techniques and strategies for ongoing and futuristic surveys.