Type Ia SNe Along Redshift: The (Si II) Ratio and the Expansion Velocities in Intermediate-z Supernovae

We present a study of intermediate-z Type Ia supernovae (SNe Ia) using empirical physical diagrams which permit the investigation of those SNe explosions. This information can be very useful to reduce systematic uncertainties of the Hubble diagram of SNe Ia up to high z. The study of the expansion velocities and the measurement of the ratio (Si II) allow subtyping of SNe Ia as done in nearby samples. The evolution of this ratio as seen in the diagram (Si II)-(t) together with (Si II)max versus (B - V)0 indicates consistency of the properties at intermediate-z compared with the nearby SNe Ia. At intermediate-z, expansion velocities of Ca II and Si II are found similar to those of the nearby sample. This is found in a sample of six SNe Ia in the range 0.033