The Standardized Candle Method for Type II Plateau Supernovae

Abstract

In this paper we study the “standardized candle method” using a sample of 37 nearby (redshift z < 0.06) Type II plateau supernovae having BV RI photometry and optical spectroscopy. An analytic procedure is implemented to fit light curves, color curves, and velocity curves. We find that the V − I color toward the end of the plateau can be used to estimate the host-galaxy reddening with a precision of (AV ) = 0.2 mag. The correlation between plateau luminosity and expansion velocity previously reported in the literature is recovered. Using this relation and assuming a standard reddening law (RV = 3.1), we obtain Hubble diagrams in the BV I bands with dispersions of 0.4 mag. Allowing RV to vary and minimizing the spread in the Hubble diagrams, we obtain a dispersion range of 0.25–0.30 mag, which implies that these objects can deliver relative distances with precisions of 12–14%. The resulting best-fit value of RV is 1.4 ± 0.1.