Two-Parameter Abundance Matching of the Fundamental Plane

Abstract

This thesis explores several topics related to galaxy evolution, primarily focusing on an improved method to connect observed galaxies to their underlying dark matter halos. We also present results on the evolution of the population of supermassive black holes (SMBHs) that reside in the centers of galaxies. We first describe our model of the growth of the supermassive black hole population, which utilizes galaxy merger trees derived from hydrodynamical cosmological simulations. We implement prescriptions for the SMBH growth due to gas accretion and mergers with other SMBHs. We also account for the time a SMBH spends orbiting in the outskirts of a galaxy that its host galaxy has just merged with, as well as the frequency of gravitation wave recoils due to SMBH mergers that can eject the resulting SMBH from the center of the galaxy. We estimate the size of the resulting population of SMBHs in the outskirts of galaxies, which could potentially be observed. We also compute the gravitational wave signal expected from merging SMBHs. We then discuss the main topic of the thesis: the development of an extended variant of the halo abundance matching method. Abundance matching statistically connects samples of observed galaxies to dark matter halos from simulations. It is a powerful tool to study the evolution of galaxy populations using the simulated halo merger trees. Standard abundance matching is based on the simple assumption that galaxy luminosity (or stellar mass) and dark matter halo mass (or maximum circular velocity) are positively and monotonically related. We extend the method by including a second galaxy and halo parameter at fixed galaxy stellar mass and halo circular velocity. We present a derivation of the relationship between present-day dark matter halo properties and the collapse time of the halo—which may be correlated with the formation time of its hosted galaxy—based on a simple spherical collapse model. We then present the results of an extended abundance matching scheme as applied to high-mass, quiescent galaxies, which shows good agreement between the observed clustering of galaxies and that predicted by the matching scheme.