Spectroscopic confirmation of high-redshift supernovae with the ESO VLT.

Abstract

We present VLT FORS1 and FORS2 spectra of 39 candidate high-redshift supernovae that were discovered as part of a cosmological study using type Ia supernovae (SNe Ia) over a wide range of redshifts. From the spectra alone, 20 candidates are spectrally classified as SNe Ia with redshifts ranging from z=0.212 to z=1.181. Of the remaining 19 candidates, 1 might be a type II supernova and 11 exhibit broad supernova-like spectral features and/or have supernova-like light curves. The candidates were discovered in 8 separate ground-based searches. In those searches in which SNe Ia at z ∼ 0.5 were targeted, over 80% of the observed candidates were spectrally classified as SNe Ia. In those searches in which SNe Ia with z > 1 were targeted, 4 candidates with z > 1 were spectrally classified as SNe Ia and later followed with ground and space based observatories. We present the spectra of all candidates, including those that could not be spectrally classified as supernova. Based on observations obtained at the European Southern Observatory using the ESO Very Large Telescope on Cerro Paranal (ESO programs 265.A-5721(A), 67.A-0361(A), 267.A-5688(A), 169.A-0382(A) and (B)). Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based in part on data collected from the Canada-France-Hawaii Telescope Corporation, which is operated by the National Research Council of Canada, le Centre National de la Recherche Scientifique de France, and the University of Hawaii. Based in part on data collected at the Cerro Tololo Inter-American Observatory, which is operated by Association of Universities for Research in Astronomy, Inc. under a cooperative agreement with the National Science Foundation. Appendix A is only available in electronic form via http://www.edpsciences.org