Abstract
We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z = 0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m ≈ 25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until 2002 April. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift SNe includes 15 at z ≥ 0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours that are consistent with the flat universe indicated by the cosmic microwave background (Spergel et al. 2003). Adopting the constraint that Ωtotal = 1.0, we obtain best-fit values of (Ωm,ΩΛ) = (0.33, 0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for ΩΛ > 0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z > 1 SNe from the ground.
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Footnotes
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CFHT: Based in part on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter-American Observatory. Keck: Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Magellan: Based in part on observations from the 6.5 m Baade telescope operated by the Observatories of the Carnegie Institution of Washington for the Magellan Consortium, a collaboration between the Carnegie Observatories, the University of Arizona, Harvard University, the University of Michigan, and the Massachusetts Institute of Technology. UH: Based in part on observations with the University of Hawaii 2.2 m telescope at Mauna Kea Observatory, Institute for Astronomy, University of Hawaii. VLT: Based in part on observations obtained at the European Southern Observatory, Paranal, Chile, under programs ESO 68.A-0427.
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Based in part on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. This research is primarily associated with proposal GO-09118.