Properties of Type Ia Supernova Host Galaxies
  We study the effect of environment on the properties of type Ia supernovae by analyzing the integrated spectra of 57 host galaxies. Integrated spectra of galaxies best represent the global properties of the host and can be used to directly compare with spectra of high-redshift galaxies. From the spectra we deduce the metallicity, current star-formation rate and star-formation history of the hosts and compare these to the supernova decline rate which is an indicator of the luminosity. Our results show no significant correlation between spiral host galaxy metallicity and SNIa light curve decline rate. The Hydrogen-alpha equivalent width (EW) of the host galaxy is an indicator the current star-formation rate compared to average rate in the past. The range of SNIa luminosities increases with decreasing EW which suggests that the variation in SNIa {56}Ni production is primarily due to progenitor mass and population age. 
P. M. Garnavich and J. Gallagher