- Garavini, G;
- Folatelli, G;
- Nobili, S;
- Aldering, G;
- Amanullah, R;
- Antilogus, P;
- Astier, P;
- Blanc, G;
- Bronder, T;
- Burns, MS;
- Conley, A;
- Deustua, SE;
- Doi, M;
- Fabbro, S;
- Fadeyev, V;
- Gibbons, R;
- Goldhaber, G;
- Goobar, A;
- Groom, DE;
- Hook, I;
- Howell, DA;
- Kashikawa, N;
- Kim, AG;
- Kowalski, M;
- Kuznetsova, N;
- Lee, BC;
- Lidman, C;
- Mendez, J;
- Morokuma, T;
- Motohara, K;
- Nugent, PE;
- Pain, R;
- Perlmutter, S;
- Quimby, R;
- Raux, J;
- Regnault, N;
- Ruiz-Lapuente, P;
- Sainton, G;
- Schahmaneche, K;
- Smith, E;
- Spadafora, AL;
- Stanishev, V;
- Thomas, RC;
- Walton, NA;
- Wang, L;
- Wood-Vasey, WM;
- Yasuda, N
We develop a method to measure the strength of the absorption features in type la supernova (SN la) spectra and use it to make a quantitative comparisons between the spectra of type la supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 ≤ z ≤ 0.912) SNe la observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of the absorption minimum in Ca II H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe la (z < 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae. © ESO 2007.