The Hubble Constant: A Summary of the HST Program for the Luminosity Calibration of Type Ia Supernovae by Means of Cepheids
Abstract
This is the summary paper of our 15 year program using the Hubble Space Telescope (HST) to determine the Hubble constant using Type Ia supernovae, calibrated with Cepheid variables in nearby galaxies that hosted them. In four previous papers new metallicity-dependent P-L relations of the Cepheids in LMC and the Galaxy were defined, a Hubble diagram for a large sample of uniformly reduced SNeIa established, the secular variation of the HST photometry tested, and the revised Cepheid distances of 37 galaxies derived. The new Cepheid distances of the subset of 10 galaxies, which were hosts of normal SNe Ia, give weighted mean luminosities in B,V,I at maximum light of -19.49, -19.46, and -19.22. These calibrate the adopted SNe Ia Hubble diagram from Paper III to give H_0 = 62.3 +/- 1.3 (random) +/- 5.0 (systematic). This is a global value because it uses the Hubble diagram between redshift limits of 3000 and 20000km/s reduced to the CMB kinematic frame, well beyond the effects of any local random and streaming motions. Local H_0 values at distances between 4.4 and 30Mpc based on Cepheids, on a complete sample of SNe Ia, and on 21cm line widths, all give H_0 within 5% of our global value. Independent support of this result comes from 47 TRGB distances on scales below 10Mpc. The agreement of H_0 on all scales from 4-300Mpc finds its most obvious explanation in the smoothing effect of vacuum energy on the otherwise lumpy gravitational field due to the non-uniform distribution of the local galaxies. The physical methods of time delay of gravitational lenses and the Sunyaev-Zeldovich effect are consistent (but with large errors) with our global value. The present value of H_0 is also not in contradiction with analyses of CMB data, because the latter depend on a number of a priori assumptions.Keywords
All Related Versions
This publication has 0 references indexed in Scilit: