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J. D. Neill (University of Victoria), M. Sullivan (University of Toronto), D. Balam (University of Victoria), P. Astier (LPNHE, CNRS-IN2P3), E. Aubourg (APC,College de France), S. Basa (LAM, CNRS), R. G. Carlberg, A. Conley (University of Toronto), S. Fabbro (CENTRA), D. Fouchez (CPPM, CNRS-IN2P3), J. Guy (LPNHE, CNRS-IN2P3), I. Hook (University of Oxford), D. A. Howell (University of Toronto), H Lafoux (DSM/DAPNIA, CEA/Saclay), R. Pain (LPNHE, CNRS-IN2P3), N. Palanque-Delabrouille (DSM/DAPNIA, CEA/Saclay), K Perrett (University of Toronto), C. J. Pritchet (University of Victoria), N. Regnault (LPNHE, CNRS-IN2P3), J. Rich (DSM/DAPNIA, CEA/Saclay), R. Taillet, S. Baumont (LPNHE, CNRS-IN2P3), J. Bronder (University of Oxford), M. Graham, E. Hsiao (University of Victoria), V. Lusset (DSM/DAPNIA, CEA/Saclay), P. Ripoche (CPPM, CNRS-IN2P3), A. Mourao (CENTRA), S. Perlmutter (LBNL), C. Tao (CPPM, CNRS-IN2P3)
We present a preliminary measurement of the distant Type Ia supernova rate derived from the Canada -- France -- Hawaii Telescope Supernova Legacy Survey (SNLS). By observing four one-square degree fields with a high temporal frequency (\langle \Delta t \rangle ~4 observer-frame days) over large fractions of a year (~6 months each field, with breaks during full moon) and using 8 meter-class telescopes for spectroscopic followup, the survey not only provides the dense time sampling needed to achieve a high completeness, but also enjoys the benefit of high quality spectroscopy to verify the Type Ia candidates and hence reduce contamination from non-Type Ia events. The goal of the survey is to measure ~700 Type Ia SNe out to z ~1 over a period of 5 years. We use the first two years of survey data to begin characterizing the Type Ia sample and explore a methodology for calculating rates from the survey. We use individual SNLS survey epoch properties to observe Monte Carlo simulations of 106 Type Ia supernovae in the redshift range 0.2 < z < 0.6, and thus derive our survey efficiency. We combine this efficiency with a carefully selected control sample of spectroscopically confirmed SNLS Type Ia SNe to derive a volumetric rate. When comparing our volumetric rate with other ground-based surveys that also use spectroscopic candidate verification, we find no evidence for significant systematic underestimation of the SN Ia rates near z = 0.5. When comparing published SN Ia rates spanning the redshift range 0.0 < z < 1.6 to models of SN Ia production, we find that neither pure delay-time models nor two component models can accommodate all the observed data.
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The author(s) of this abstract have provided an email address for comments about the abstract: neill@uvic.ca
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.