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The neutral interstellar medium in luminous compact blue galaxies

Posted on:2005-02-02Degree:Ph.DType:Dissertation
University:University of Hawai'i at ManoaCandidate:Garland, Catherine AFull Text:PDF
GTID:1450390011950601Subject:Physics
Abstract/Summary:
We have completed a single-dish survey of the neutral interstellar medium in 20 local Luminous Compact Blue Galaxies (LCBGs). The sample was chosen to have rest-frame properties of intermediate redshift LCBGs. The number density of such galaxies decreases by at least ten times from z ∼ 1 to today. As well, LCBGs dominate the star formation rate density of the Universe at z ∼ 1. Our goals, as part of a multi-wavelength survey of LCBGs, were to characterize this galaxy class and investigate the evolutionary possibilities through observations of atomic hydrogen (H I) and carbon monoxide (CO).; Using the Green Bank Telescope we acquired 21 cm H I spectra of our sample. We found local LCBGs to be gas-rich, and half to have mass-to-light ratios ∼ten times smaller than local galaxies of similar luminosities, verifying results from intermediate redshift studies of LCBGs.; With a variety of millimeter telescopes, we observed the three lowest rotational transitions of CO. We found that the average gas conditions in local LCBGs are similar to those found in star forming regions in our Galaxy. LCBGs have low ratios of CO to H I, typically ∼5%. Assuming constant star formation rates, 80% will exhaust their supply of neutral gas in less than 5 Gyrs, consuming the molecular gas in less than 200 Myrs.; We have begun an interferometric study using the Very Large Array and the Owens Valley Radio Observatory. In a sub-sample of local LCBGs, we find the H I distributions are disturbed, indicating recent or ongoing interactions. The velocity fields are dominated by non-circular motions. We find we have overestimated the dynamical and H I masses in some galaxies, by up to 25% and 75%, respectively.; If the current burst of star formation is the last, and considering the dynamical mass, neutral gas, luminosity, metallicity, and morphological properties of local LCBGs, their most likely evolutionary paths are toward Magellanic spiral, irregular, and dwarf elliptical galaxies. Under these assumptions, dwarf ellipticals are the most plausible evolutionary outcome given the typical colors and metallicities of these galaxy types. However, as LCBGs are morphologically and spectroscopically diverse, they are unlikely to evolve into one galaxy class.
Keywords/Search Tags:Lcbgs, Galaxies, Neutral, Local, Galaxy
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