The Power of Spectrophotometry: K-correction-free Type Ia Supernova Light Curves from the Nearby Supernova Factory

Abstract

International audienceStandard Type Ia supernova (SN Ia) photometry light curve fits introduce a convolution of an average ''template'' spectral model, redshifted to observer frame -- a K-correction. Uncertainties in the template, or a mismatch between the template and an observed SN Ia SED introduces errors in the K-correction. Minimizing or eliminating this systematic error is key in the new era of precision SN Ia cosmology. The Nearby Supernova Factory has collected a dataset of spectrophotometric SN Ia time series, allowing us to recreate rest-frame light curves of each SN, given its host redshift and synthetic filter (and instrument) throughputs. This effectively eliminates the K-correction. The resulting SN Ia light curves produce a smaller dispersion in nearby Hubble diagram residuals when compared to the standard approach. Light curves from synthetic bands centered on particular features or wavelength regions are also investigated, with an emphasis on their utility in photometric subclassification