Tests of Environmental Effects on SN Ia Production

The largely unknown type Ia supernova (SN Ia) mechanism remains one of the largest sources of possible systematic uncertainty in achieving precise measures of dark energy. The host galaxy environments of SNe Ia provide our best opportunity for constraining the mechanism(s) of the SN Ia progenitor system, i.e., the stars involved, the incubation times, and the sensitivity of SNe Ia to changes in the local gas-phase metallicity. The latter can affect the luminosity of the resultant Ia event, and possibly the success in ultimately yielding a SN Ia event. We seek to solidify possible environmental trends in SN Ia rates from direct measures of host galaxy properties, using the sample collected by the Nearby Galaxies Supernova Search (NGSS) project. The purpose of this study is to uncover which has the greatest influence on SN Ia production efficiency: parent population age, rate of star- formation, or metallicity. Here, we propose to begin our analysis using any of NOAO-access 4m + spectrograph to obtain broad SEDs, R_23 metallicities, and star formation rates for 14 of the ~30 host galaxies (all z⪉0.1) from the NGSS sample. These data will be combined with the remaining sample to be sought in the 2010B and future semesters. The sample will provide a validity test of the mostly indirect trends being established for SNe Ia from the SNfactory, SDSS, and other surveys, and ultimately steer future investigations towards more precise SN Ia cosmology.