Program: GS-2010B-Q-82

The recent discovery of correlations between Type Ia Supernova (SN Ia) peak luminosity and the parameters defining their host galaxy stellar populations has important implications for their use as standardised candles. Using new samples of low-redshift SNe Ia located with the Palomar Transient Factory (PTF), a rolling transient search in the local universe, we propose a comprehensive campaign to study in detail the host galaxies in which SNe Ia explode. We aim to establish which physical variable (metallicity or age) primarily drives the SN Ia luminosity variations using high signal-to-noise spectroscopy of their environments. These data will also improve the derivation of SN Ia "delay-time" distributions, and place tighter constraints on the nature of their progenitor systems. Evolution in SN Ia properties is now the largest single systematic in SN Ia cosmology, and detailed study of their environments provides a realistic opportunity to improve their use for studying dark energy.