We present 139 spectra of 124 Type Ia supernovae (SNeIa) that were
observed at the ESO/VLT during the first three years of the
Canada-France-Hawai Telescope (CFHT) Supernova Legacy Survey (SNLS).
This homogeneous data set is used to test for redshift evolution of
SNeIa spectra, and will be used in the SNLS 3rd year cosmological
analyses. Spectra have been reduced and extracted with a dedicated
pipeline that uses photometric information from deep CFHT Legacy Survey
(CFHT-LS) reference images to trace, at sub-pixel accuracy, the position
of the supernova on the spectrogram as a function of wavelength. It also
separates the supernova and its host light in 60% of cases. The
identification of the supernova candidates is performed using a
spectrophotometric SNIa model. A total of 124 SNeIa, roughly 50% of the
overall SNLS spectroscopic sample, have been identified using the
ESO/VLT during the first three years of the survey. Their redshifts
range from z=0.149 to z=1.031. The average redshift of the sample is
z=0.63+/-0.02. This constitutes the largest SNIa spectral set to date in
this redshift range. The spectra are presented along with their best-fit
spectral SNIa model and a host model where relevant. In the latter case,
a host subtracted spectrum is also presented. We produce average spectra
for pre-maximum, maximum and post-maximum epochs for both z<0.5 and
z>=0.5 SNeIa. We find that z<0.5 spectra have deeper intermediate
mass element absorptions than z>= 0.5 spectra. The differences with
redshift are consistent with the selection of brighter and bluer
supernovae at higher redshift.
