Understanding The Galaxy-Halo Connection Through Galaxy Group Catalogues

Abstract

The Universe is comprised of structures on all scales, ranging from stars and planets to galaxies and clusters. These structures form part of a much bigger web-like structure built with systems of galaxies, filaments, walls, and cosmic voids between galaxies. The Universe is comprised of Large-Scale Structure, in which galaxies form, evolve, and eventually die. Within this framework, galaxies constitute the primary objects in the observed Universe, and act as the building blocks of Large-Scale Structure. In this dissertation, I undertake an extensive analysis of the galaxy-halo connection, which refers to the statistical connection between the luminous matter in the Universe (galaxies) and the dark matter in the Universe, with the help of galaxy group catalogues. With the help of cosmological simulations and a set of distinct galaxy group catalogues, I analyze the stellar content of galaxy groups, and present a set of value-added galaxy catalogues for three galaxy samples. Then, I utilize these galaxy catalogues to better understand the effect of galactic conformity, and conclude that this effect is only observed at very large scales. Lastly, I present a new methodology to determine the mass of a galaxy’s host dark matter halo by employing machine learning techniques. This methodology is able to outperform former traditional methods of estimated a galaxy’s host dark matter halo mass.