The Hubble Constant from Type Ia Supernova Calibrated with the Linear and Non-Linear Cepheid Period-Luminosity Relations

It is well-known that the peak brightness of the Type Ia supernovae calibrated with Cepheid distances can be used to determine the Hubble constant. The Cepheid distances to host galaxies of the calibrating supernovae are usually obtained using the period-luminosity (PL) relation derived from Large Magellanic Cloud (LMC) Cepheids. However recent empirical studies provide evidence that the LMC PL relation is not linear. In this Letter we determine the Hubble constant using both the linear and non-linear LMC Cepheid PL relations as calibrating relations to four galaxies that hosted Type Ia supernovae. Our results suggest that the obtained values of the Hubble constant are similar. However a typical error of ∼ 0.03mag. has to be added (in quadrature) to the systematic error for the Hubble constant when the linear LMC PL relation is used, assuming that the LMC PL relation is indeed non-linear. This is important in minimizing the total error of the Hubble constant in the era of precision cosmology. The Hubble constants calibrated from the linear and nonlinear LMC PL relation are H0 = 74.92± 2.28(random)± 5.06(systematic) km s −1 Mpc and H0 = 74.37 ± 2.27(random) ± 4.92(systematic) km s −1 Mpc, respectively. Hubble constants calculated using the Galactic PL relations are also briefly discussed and presented in the last section of this Letter. Subject headings: distance scale — Cepheids — galaxies: distances and redshifts