Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010phdt........73c&link_type=abstract
ProQuest Dissertations And Theses; Thesis (Ph.D.)--Indiana University, 2010.; Publication Number: AAT3409096; ISBN: 978112406107
Astronomy and Astrophysics
Astronomy
Scientific paper
The composition of the universe has greatly changed since the first matter condensed from the primordial soup of the Big Bang. As galaxies have grown and evolved over the past Hubble time, massive luminous galaxies have built up more heavy elements than their low mass counterparts. While sundry physical mechanisms have been proposed to account for this observed trend, the physical connection between galaxy mass and metallicity has evaded the understanding of astronomers for several decades. In order to gain a greater understanding of this metallicity-luminosity relation and the physical drivers behind the chemical evolution of galaxies, we have performed a detailed study of galaxies in both isolated and non-isolated environments: namely, galaxies in the local volume (D ≤ 5 Mpc) and galaxy members belonging to the M81 group. Our results from studying the M81 group imply that recent interactions among the central galaxies in this group, rather than mechanisms intrinsic to the galaxies, are likely responsible for the anomalously high abundances in three cluster members. While tidal interactions can alter the chemical make up the galaxies involved, the well established metallicity-luminosity relation indicates a more universal chemical evolution. To further explore this idea, we analyze galaxy abundances, stellar & gas distributions, and kinematics from both new and archival observations of forty-five low mass galaxies within 5 Mpc of the Milky Way. Our results indicate that these galaxies occupy a different mass-to-light ratio parameter space than their larger counter parts. Our study of the local volume explores the effects of various galaxy attributes such as mass, star formation rate, gas mass fraction, and the mass distribution that offer more concrete connections with the evolution of the system. We show that none of the attributes measured in this study exhibit more correlation with metallicity (measured via nebular oxygen abundances) than does the luminosity. Additionally, we find that when the chemical composition of galaxies is viewed in terms of the effective yield, galaxies that are more centrally concentrated appear to have a lower effective yield. We discuss possible scenarios which could result in the observed correlations with oxygen abundance.
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