Volume 470, Number 2, August I 2007
|Page(s)||411 - 424|
|Section||Cosmology (including clusters of galaxies)|
|Published online||24 April 2007|
Quantitative comparison between type Ia supernova spectra at low and high redshifts: a case study
Department of Physics, Stockholm University, Albanova University Center, 106 91 Stockholm, Sweden e-mail: email@example.com
2 LPNHE, CNRS-IN2P3, University of Paris VI & VII, Paris, France
3 Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101, USA
4 E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
5 Osservatorio Astronomico di Padova, INAF, vicolo dell'Osservatorio 5, 35122 Padova, Italy
6 Department of Physics, University of Oxford, Nuclear & Astrophysics Laboratory, Keble Road, Oxford OX1 3RH, UK
7 Colorado College, 14 East Cache La Poudre St., Colorado Springs, CO 80903
8 Department of Physics, University of California Berkeley, Berkeley, 94720-7300 CA, USA
9 American Astronomical Society, 2000 Florida Ave, NW, Suite 400, Washington, DC, 20009 USA
10 Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo 181-0015, Japan
11 CENTRA e Dep. de Fisica, IST, Univ. Tecnica de Lisboa
12 Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37240, USA
13 Department of Astronomy and Astrophysics, University of Toronto, 60 St. George St., Toronto, Ontario M5S 3H8, Canada
14 National Astronomical Observatory, Mitaka, Tokyo 181-0058, Japan
15 European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
16 Isaac Newton Group, Apartado de Correos 321, 38780 Santa Cruz de La Palma, Islas Canarias, Spain
17 Department of Astronomy, University of Barcelona, Barcelona, Spain
18 Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
19 Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, 277 8582 Japan
Accepted: 21 March 2007
We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 ≤ z ≤ 0.912) SNe Ia 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 Ia (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.
Key words: stars: supernovae: general / cosmology: early Universe
© ESO, 2007
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