GMOS optical long-slit spectroscopy at the Gemini-North telescope was
used to classify targets from the Supernova Legacy Survey (SNLS) from
July 2005 and May 2006 - May 2008. During this time, 95 objects were
observed. Where possible the objects' redshifts (z) were measured from
narrow emission or absorption features in the host galaxy spectrum,
otherwise they were measured from the broader supernova features. We
present spectra of 68 confirmed or probable SNe Ia from SNLS with
redshifts in the range 0.17 \leq z \leq 1.02. In combination with
earlier SNLS Gemini and VLT spectra, we used these new observations to
measure pseudo-equivalent widths (EWs) of three spectral features - CaII
H&K, SiII and MgII - in 144 objects and compared them to the EWs of
low-redshift SNe Ia from a sample drawn from the literature. No signs of
changes with z are seen for the CaII H&K and MgII features.
Systematically lower EW SiII is seen at high redshift, but this can be
explained by a change in demographics of the SNe Ia population within a
two-component model combined with an observed correlation between EW
SiII and photometric lightcurve stretch.
