Committee ChairImpey, Christopher D.
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PublisherThe University of Arizona.
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AbstractThis dissertation briefly presents the results of a survey for galaxies that have been overlooked by previous surveys because their surface brightness, or brightness per unit area on the night sky, is too low. This dissertation then makes use of the survey results to estimate the density of these galaxies and to delineate some of their properties. Chapter 1 describes the selection bias against finding galaxies of low surface brightness and outlines the importance of these galaxies for a more complete knowledge of the true local galaxy population. Chapter 2 discusses the techniques employed for identifying low surface brightness (LSB) galaxies for the survey, calibrating the photometry, and estimating the survey incompleteness as a function of galaxy parameters. Chapter 3 presents luminosity functions for the low surface brightness galaxies identified in the present survey, and for a combined sample of low surface brightness and high surface brightness galaxies. The overall space density of low surface brightness galaxies is about one-fourth to one-third as great as the density determined from standard field galaxy luminosity functions, and that the total luminosity density due to these low surface brightness galaxies is about one-third to one-half the level derived from other surveys. Chapter 4 presents 21 cm profiles and CCD surface photometry for a subset of the low surface brightness spiral galaxies found by the survey. The general trend of the LSB galaxies in the Tully-Fisher relation, relative to the trend of higher surface brightness galaxies, forms the basis of the conclusion that LSB spiral generally have mass-to-light ratios comparable to that of higher surface brightness spirals but with a much larger scatter. Various possible reasons for the higher scatter are explored. Chapter 5 presents CCD surface photometry and optical spectroscopy for a sample of eight low surface brightness spiral galaxies that are extraordinary because of their large physical sizes and high total luminosities. The properties of these galaxies are analyzed and compared to those of more normal spirals. Chapter 6 summarizes the findings of the preceding chapters and presents some ideas for future investigations.