Towards a Cosmological Hubble Diagram for Type II-P Supernovae
Abstract
We present the first high-redshift Hubble diagram for Type II-P supernovae (SNe II-P) based upon five events at redshift up to z~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 SNe II-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, a cross-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.
Cite
@article{arxiv.astro-ph/0603535,
title = {Towards a Cosmological Hubble Diagram for Type II-P Supernovae},
author = {Peter Nugent and Mark Sullivan and Richard Ellis and Avishay Gal-Yam and Douglas C. Leonard and D. Andrew Howell and Pierre Astier and Raymond G. Carlberg and Alex Conley and Sebastien Fabbro and Dominique Fouchez and James D. Neill and Reynald Pain and Kathy Perrett and Chris J. Pritchet and Nicolas Regnault},
journal= {arXiv preprint arXiv:astro-ph/0603535},
year = {2009}
}
Comments
36 pages, 16 figures, accepted for publication in ApJ