Spectroscopic Diversity of Type Ia Supernovae in the Near-Infrared

Eric Hsiao
University of Victoria


The photometric studies of Type Ia supernovae (SNe Ia) in the optical have demonstrated that they can be calibrated to be standard candles. More remarkably, they may be considered true standard candles in the near-infrared. We explore whether the spectroscopic properties in the near-infrared are similarly uniform. We also look at the rest frame I band, which is of interest for near-infrared observations of high-redshift SNe Ia. A set of mean spectral templates is constructed by combining a large sample of observed spectra and light curves using methods developed by Hsiao et al. (2007). The spectroscopic diversity around the template is then quantified. In the near-infrared, the spectroscopic temporal evolution is shown to be quite uniform at all phases and slow around the near-infrared maximum light, further validating the use of near-infrared luminosity of SNe Ia as standard candles. Possible correlations of spectral features with the light curve width are also examined.