Local Environment Of SNLS5 Type Ia Supernovae
Résumé
Type Ia supernovae constitute a powerful probe of dark energy equation of state
and expansion rate, assuming an empirical standardization process. As supernovae
lie in galactic regions that evolve with redshift, we expect that their
luminosities depend on local properties. We measure local U − V rest-frame
colors in regions of 3 kpc around the explosion location and find that, under
the assumption of a bimodal distribution, local color correlates to Hubble
diagram residuals at a significance of 7σ. This is more significant than any
other global quantity we measure. Local effects must be included in the
standardization.