The Standardized Candle Method for Type Ii Plateau Supernovae

In this paper, we study the "standardized candle method" using a sample of 37 nearby (redshift z < 0.06) Type II plateau supernovae having BVRI 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 σ( A V ) = 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 ( R V = 3.1), we obtain Hubble diagrams (HDs) in the BVI bands with dispersions of ∼0.4 mag. Allowing R V to vary and minimizing the spread in the HDs, 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 R V is 1.4 ± 0.1.