The Standard Candle Method for Type II-Plateau Supernovae

In this thesis we study the "standardized candle method" using a sample of 37 nearby (redshift < 0.06) Type II-plateau supernovae with BVRI photometry and optical spectroscopy. An analytic procedure is implemented to fit light, color, and velocity curves. We find that the V-I color toward the end of the plateau can be used to estimate host-galaxy reddening with a precision of 0.2 mag. The luminosity-expansion velocity relation previously reported in the literature is recovered. Using this relation and assuming a standard reddening law (R_V = 3.1), we obtain Hubble diagrams in the BVI bands with approximate dispersions of 0.4 mag. Allowing R_V to vary and minimizing the spread in the Hubble diagrams, we obtain a dispersion of 0.25-0.30 mag, which implies that these objects can deliver distances with a precision of 12-14 %. The resulting value of R_V is 1.4 +/- 0.1. Using two supernovae with known Cepheid host-galaxy distances, we obtain H_0 = 70 +/- 8 km/s/Mpc, in very good agreement with the average value obtained with other modern, reliable methods.