TWENTY-THREE HIGH-REDSHIFT SUPERNOVAE FROM THE INSTITUTE FOR ASTRONOMY DEEP SURVEY: DOUBLING THE SUPERNOVA SAMPLE AT z > 0.7

摘要

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 deg~2 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 Ω~(total) = 1.0, we obtain best-fit values of (Ω_m, Ω_Λ) = (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 Ω_Λ > 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.