DETERMINATION OF THE HUBBLE CONSTANT USING A TWO-PARAMETER LUMINOSITY CORRECTION FOR TYPE Ia SUPERNOVAE

In this paper, we make a comprehensive determination of the Hubble constant H0 by using two parameters—the B − V color and the rate of decline ∆m15—to simultaneously standardize the luminosities of all nearby Cepheid-calibrated type Ia supernovae (SNe Ia) and those of a larger, more distant sample of 29 SNe Ia. Each group is treated in as similar a manner as possible in order to avoid systematic effects. A simultaneous χ minimization yields a standardized absolute luminosity of the Cepheid-calibrated supernovae as well as the Hubble constant obtained from the more distant sample. We find H0 = 62 km s −1 Mpc−1 and a standardized absolute magnitude of -19.46. The sensitivity of H0 to a metallicity dependence of the Cepheid-determined distances is investigated. The total uncertainty δH0, dominated by uncertainties in the primary Cepheid distance indicator, is estimated to be 5 km s−1 Mpc−1. Subject headings: cosmology: distance scale–supernovae: general