Quantifying Spectral Features of Type Ia Supernovae
  We introduce a new technique to quantify highly structured spectra for which
the definition of continua or spectral features in the observed flux spectra is
difficult. The method employs wavelet transformation which allows the
decomposition of the observed spectra into different scales. A procedure is
formulated to define the strength of spectral features so that the measured
spectral indices are independent of the flux levels and are insensitive to the
definition of continuum and also to reddening. This technique is applied to
Type Ia supernovae spectra, where correlations are revealed between the
luminosity and spectral features. The current technique may allow for
luminosity corrections based on spectral features in the use of Type Ia
supernovae as cosmological probe.
