Towards a Cosmological Hubble Diagram for Type II-PSupernovae
We present the first high-redshift Hubble diagram for Type II-P supernovae (SNe II-P) based upon five events at redshift upto z {approx}0.3. This diagram was constructed using photometry from the Canada-France-Hawaii Telescope Supernova Legacy Survey and absorption line spectroscopy from the Keck observatory. The method used to measure distances to these supernovae is based on recent work by Hamuy&Pinto (2002) and exploits a correlation between the absolute brightness of SNeII-P and the expansion velocities derived from the minimum of the Fe II 516.9 nm P-Cygni feature observed during the plateau phases. We present three refinements to this method which significantly improve the practicality of measuring the distances of SNe II-P at cosmologically interesting redshifts. These are an extinction correction measurement based on the V-I colors at day 50, across-correlation measurement for the expansion velocity and the ability to extrapolate such velocities accurately over almost the entire plateau phase. We apply this revised method to our dataset of high-redshift SNe II-P and find that the resulting Hubble diagram has a scatter of only 0.26 magnitudes, thus demonstrating the feasibility of measuring the expansion history, with present facilities, using a method independent of that based upon supernovae of Type Ia.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE; National Aeronautics and Space Administration GrantHST-HF-01158.01-A and Contract NAS 5-26555, National Science FoundationAward AST-0401479
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 889627
- Report Number(s):
- LBNL-59881; ASJOAB; R&D Project: 43CX01; BnR: 400409900; TRN: US0700852
- Journal Information:
- Astrophysical Journal, Vol. 645, Issue 2; Related Information: Journal Publication Date: 07/10/2006; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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