SALT: A spectral adaptive light curve template for type la supernovae

Abstract

We present a new method to parameterize type la Supernovae (SN Ia) multi-color light curves. The method was developed in order to analyze the large number of SN la multi-color light curves measured in current high-redshift projects. The technique is based on empirically modeling SN la luminosity variations as a function of phase, wavelength, a shape parameter, and a color parameter. The model is trained with a sample of well-measured nearby SN la and then tested with an independent set of supernovae by building an optimal luminosity distance estimator that combines the supernova rest-frame luminosity, shape parameter, and color reconstructed with the model. The distances we measure using B- and V-band data show a dispersion around the Hubble line comparable or lower than obtained with other methods. With this model, we are able to measure distances using U- and B-band data with a dispersion of 0.16 ± 0.05 around the Hubble line. © ESO 2005.