Physical Sciences and Mathematics Commons^™

Bayesian Anatomy Of Galaxy Structure, Ilsang Yoon

Open Access Dissertations

In this thesis I develop Bayesian approach to model galaxy surface brightness and apply it to a bulge-disc decomposition analysis of galaxies in near-infrared band, from Two Micron All Sky Survey (2MASS). The thesis has three main parts.

First part is a technical development of Bayesian galaxy image decomposition package Galphat based on Markov chain Monte Carlo algorithm. I implement a fast and accurate galaxy model image generation algorithm to reduce computation time and make Bayesian approach feasible for real science analysis using large ensemble of galaxies. I perform a benchmark test of Galphat and demonstrate significant improvement in parameter …

High-Resolution Ultraviolet Spectroscopy Of Gas In Galaxy Halos And Large-Scale Structures, Limin Song

Open Access Dissertations

This dissertation presents spectroscopic studies of gas in galaxy halos and large-scale structures through high-resolution quasar absorption lines. The broad goal of this effort is to learn how galaxies acquire their gas and how they return it to the intergalactic medium, or more generally, how galaxies interact with their environment. The study of the absorption lines due to the extraplanar 21cm "Outer Arm'' (OA) of the Milky Way toward two quasars, H1821+643 and HS0624+6907, provides valuable insight into the gas accretion processes. It yields the following results. (1) The OA is a multiphase cloud and high ions show small but …