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Title: The physics of interacting galaxies
Author: Cullen, H. E.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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This thesis investigates interacting galaxies using two complementary approaches: a statistical study of star formation in a large sample of close pairs of galaxies drawn from the Sloan Digital Sky Survey (SDSS) and a study of the ISM and star forming properties of a small sample of interacting pairs taken from Arp’s atlas, each comprising one early- and one late-type system (E+S pairs). The first part of this thesis investigates the effect of galaxy interaction on star formation using a large volume- and luminosity-limited sample of galaxies drawn from the SDSS. Star-formation rates were calculated from extinction and aperture corrected Hα luminosities and, for a subset of systems, IRAS data. The mean specific star-formation rate is found to be strongly enhanced for projected separations of less than 25 kpc. For late-type galaxies, the correlation extends out to projected separations of 300 kpc and is most pronounced in actively star-forming systems. The specific star-formation rate of observed to decrease with increasing recessional velocity difference, although the magnitude of this effect is small compared to that associated with the projected separation. No dependence of star formation enhancement on the morphological type or mass of the companion galaxy is observed. This second part of this thesis presents a study of the ISM and star forming properties of nine E+S pairs. Detailed case studies were undertaken for two of the pairs, Arp 140 and Arp 104, both of which display extended tidal tails in their H1 morphology. These two pairs differ markedly. Despite Arp 140’s relatively evolved interaction and weakly barred potential, NGC 275, the late-type component, has neither a molecular gas nor star formation distribution that is centrally condensed. Instead, the molecular gas and HII regions display an unusual anti-correlation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available