The rise times of low and high redshift type Ia supernovae are consistent
We present a self-consistent comparison of the rise times for low- and high-redshift Type Ia supernovae. Following previous studies, the early light curve is modeled using a t2 law, which is then mated with a modified Leibundgut template light curve. The best-fit t2 law is determined for ensemble samples of low- and high-redshift supernovae by fitting simultaneously for all lightcurve parameters for all supernovae in each sample. Our method fully accounts for the non-negligible covariance amongst the light curve fitting parameters, which previous analyses have neglected. Contrary to Riess et al. (1999a), we find fair to good agreement between the rise times of the low and high-redshift Type Ia supernovae. The uncertainty in the rise time of the high-redshift Type Ia supernovae is presently quite large (roughly + or - 1.5 days statistical), making any assertion of evolution based on a comparison of rise times premature. Furthermore, systematic effects on rise time determinations from th e high-redshift observations, due to the form of the late-time light curve and the manner in which the light curves of these supernovae were sampled, can bias the high-redshift rise time determinations by up to +1.5 or -2.2 days under extreme situations. The peak brightnesses - used for cosmology - do not suffer any significant bias.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of High Energy and Nuclear Physics. Division of High Energy Physics (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 771730
- Report Number(s):
- LBNL-44232; ANJOAA; R&D Project: 419401; TRN: AH200104%%534
- Journal Information:
- Astronomical Journal, Vol. 119, Issue 5; Other Information: PBD: 14 Sep 1999; ISSN 0004-6256
- Country of Publication:
- United States
- Language:
- English
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