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Conference papers

SNLS: The Supernova Type Ia Rate at z = 0.47

Abstract : 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 (< $\delta$ > ~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 $10^6 $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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Submitted on : Thursday, November 8, 2007 - 3:18:43 PM
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J. D. Neill, M. Sullivan, D. Balam, P. Astier, E. Aubourg, et al.. SNLS: The Supernova Type Ia Rate at z = 0.47. American Astronomical Society Meeting 207, Jan 2006, Washington, DC, United States. pp.1177. ⟨in2p3-00186269⟩



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