Probing the Nature of Dark Matter in the Universe

Abstract

The dark matter is the most dominating matter candidate and a key driving force for the structure formation in the universe. Despite decade-long searches, the precise nature and particle properties of dark matter are still unknown. The standard cold dark matter candidate, the Weakly Interacting Massive Particle(WIMP) can successfully describe the large-scale features of the universe. However, when it comes to the scales comparable to a galaxy or a group of galaxies, it fails to explain the observations. The nature of the small-scale anomalies suggests a lower amount of dark matter at the scales of interest and can be tackled with di erent strategies. The simulation suites, used to produce the small-scale universe theoretically, can be equipped with varieties of baryonic phenomena, leading to a better agreement with observation. Another way is to use some new dark matter candidate altogether that reduces the small-scale power. Many such alternative dark matter candidates have been suggested and explored in the literature. The aim of the work presented in this thesis is to study the e ects of small-scale power reduction due to new dark matter physics on di erent cosmological observables.