Studying the Evolution of the M31 Dwarf Galaxies

by Ho, Ngoc Nhung, Ph.D., YALE UNIVERSITY, 2013, 155 pages; 3578353


We present detailed studies on the stellar kinematics and metallicity of dwarf galaxies surrounding the Andromeda galaxy (M31), the nearest massive host outside of our own Milky Way (MW) galaxy. Detailed kinematical and metallicity studies of the dwarf galaxies of the MW have been ongoing and have helped answer important questions on the nature of these dwarfs. However, in order to study their evolution, we need to look at dwarf systems around other hosts. We determine detailed kinematics of And II and show that it is a rotationally dominated system, placing it among a small group of Local Group dwarf spheroidals that exhibit strong rotation. We show that, as a group, the brightest dwarfs of the M31 system have similar metallicity properties to the MW dwarf system. We derive a metallicity-luminosity relation for the dwarf populations around both hosts and show them to be in agreement, showing that the main factor in the average metal abundance of a dwarf galaxy is its mass. We then derived radial metallicity profiles and show that, in contrast to previous studies, we do not observe a relation between the dynamical state of a dwarf and the presence of a metallicity gradient. Lastly, we derive the first stellar rotation curve of a Local Group dwarf irregular using spectroscopy of individual stars within the dwarf galaxy IC 10. We show that the stellar component exhibits rotation that is aligned with the neutral gas-disk that it is embedded in. In conclusion, we find that the dwarfs of the M31 system exhibit the same amount of complexity in their kinematics and metallicities as those in the MW and that, while individually different, as a group they follow similar scaling relations.

AdviserMarla C. Geha
Source TypeDissertation
SubjectsAstrophysics; Astronomy
Publication Number3578353

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