Nature versus nurture: how parent galaxy environments affect the rates and properties of their Type Ia supernovae

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dc.contributor.author Graham, Melissa Lynn
dc.date.accessioned 2010-08-26T17:40:14Z
dc.date.available 2010-08-26T17:40:14Z
dc.date.copyright 2010 en
dc.date.issued 2010-08-26T17:40:14Z
dc.identifier.uri http://hdl.handle.net/1828/2976
dc.description.abstract Supernovae of Type Ia, SNe Ia, are currently the most powerful tool of modern cosmology, but their progenitor scenario is not yet well constrained. Recent studies of SN Ia rates in radio-loud early-type galaxies, and members of rich clusters, suggest a possible influence on SN Ia explosions outside of the established correlation with the age of the parent galaxy's stellar population (via the current specific star formation rate, sSFR). These rates were used to show that the characteristics of SN Ia progenitor systems may be inconsistent with theoretical expectations of the most popular scenarios. The astrophysical question of this thesis is: do parent galaxy and environment influence the rates and properties of Type Ia supernovae, and, if so, how? Towards this end, we combine the database of Type Ia supernovae from the Canada-France-Hawaii Telescope's Supernova Legacy Survey with publicly available catalogs including: galaxy photometric and spectroscopic redshifts, radio and infrared sources, and members of galaxy groups and clusters. This is the most comprehensive set of multi-wavelength host properties and environment parameters for intermediate redshift Type Ia supernovae yet compiled. We present the SNLS SN Ia rate per unit mass in a variety of parent galaxy and environment samples. We also statistically assess the probability of discrepancies between our rates, those of previous works at low redshift, rates in the general population of galaxies, and predictions of established empirical SN Ia rate models. In general, we do not find statistically significant evidence for SN Ia rate enhancements over the general population in galaxies which are radio-loud, infrared-bright, or associated with galaxy groups and clusters. In cases where we do find a suggestive rate enhancement, it is always with less than 2-sigma confidence. These rates agree with established empirical rate models, which in turn are consistent with theoretical expectations of the most plausible progenitor scenarios. Furthermore, we find the properties of SNLS SNe Ia in these types of hosts and environments are consistent with the predictions of these scenarios. We conclude that, aside from the established correlation with host sSFR, no conclusive evidence is observed with SNLS data for strictly environmental effects on SN Ia rates. This supports their continued status as cosmological standard candles. en
dc.language English eng
dc.language.iso en en
dc.rights Available to the World Wide Web en
dc.subject extragalactic en
dc.subject supernovae en
dc.subject.lcsh UVic Subject Index::Sciences and Engineering::Physics::Astronomy en
dc.title Nature versus nurture: how parent galaxy environments affect the rates and properties of their Type Ia supernovae en
dc.type Thesis en
dc.contributor.supervisor Pritchet, Christopher J.
dc.degree.department Dept. of Physics and Astronomy en
dc.degree.level Doctor of Philosophy Ph.D. en
dc.identifier.bibliographicCitation Graham et al. 2008, Astronomical Journal, 135,1343 en
dc.identifier.bibliographicCitation Graham et al. 2010, Astronomical Journal, 139, 594 en

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