Dissecting the Surface Brightness of Galaxies

Abstract

Mass and angular momentum are two fundamental quantities governing the evolution of galaxies. Nevertheless, because measuring the angular momentum of galaxies is difficult and requires significant resource, the effect of angular momentum on galaxy evolution remains poorly understood in observations. This dissertation research uses the surface brightness of galaxy disks as a proxy for the angular momentum and studies its effect on galaxy evolution. I have measured the surface brightness profiles from multi-wavelength photometry of 501 nearby late-type galaxies selected from the ALFALFA survey. With this homogeneous data set, I can investigate the surface brightness dependence on galaxy properties at fixed stellar mass. I have concluded that at fixed stellar mass, lower surface brightness galaxies contains more hydrogen gas, are less efficient in forming stars and consist of stars of lower abundance of heavy elements. However, the average ages of galaxies do not appear to depend on the surface brightness. Combining analytical chemical evolution models, I have constrained the gas inflow and outflow rates relative to the star-formation rate. At fixed mass, lower surface brightness galaxies experienced higher accretion rates. The surface brightness dependence is stronger in low mass galaxies. The model is not able to put meaningful constraints on the properties of gas outflow. Lastly, I have investigated the intriguing bimodal distribution of surface brightness found in the literature. I show that the bar-driven secular evolution redistributes the matter angular momentum, therefore, alters the surface brightness distribution.