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Quantitative comparison between type Ia supernova spectra at low and high redshifts: a case study

  • Author(s): 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
  • et al.
Abstract

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.

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