Light-curve parameters from the SNLS

SN data alone require cosmic acceleration at >99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z=1.4) in a flat universe, we find w=-0.91^+0.16^_-0.20_(stat)^+0.07^_-0.14_(sys) from SNe only, consistent with a cosmological constant.

Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models.