The HST Key Project on the Extragalactic Distance Scale XXV. A Recalibration of Cepheid Distances to Type Ia Supernovae and the Value of the Hubble Constant

• Main Authors: Gibson, Brad K, Stetson, Peter B, Freedman, Wendy L, Mould, Jeremy R, Kennicutt,Jr, Robert C, Huchra, John P, Sakai, Shoko, Graham, John A, Fassett, Caleb I, Kelson, Daniel D, Ferrarese, Laura, Hughes, Shaun M. G, Illingworth, Garth D, Macri, Lucas M, Madore, Barry F, Sebo, Kim M, Silbermann, Nancy A
• Format: Journal Article
• Language: English
• Published: 13.08.1999
• Subjects: Physics - Astrophysics of Galaxies; Physics - Cosmology and Nongalactic Astrophysics; Physics - Earth and Planetary Astrophysics; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.astro-ph/9908149

Astrophys.J.529:723-744,2000 Cepheid-based distances to seven Type Ia supernovae (SNe)-host galaxies have been derived using the standard HST Key Project on the Extragalactic Distance Scale pipeline. For the first time, this allows for a transparent comparison of data accumulated as part of three different HST projects, the Key Project, the Sandage et al. Type Ia SNe program, and the Tanvir et al. Leo I Group study. Re-analyzing the Tanvir et al. galaxy and six Sandage et al. galaxies we find a mean (weighted) offset in true distance moduli of 0.12+/-0.07 mag -- i.e., 6% in linear distance -- in the sense of reducing the distance scale, or increasing H0. Adopting the reddening-corrected Hubble relations of Suntzeff et al. (1999), tied to a zero point based upon SNe~1990N, 1981B, 1998bu, 1989B, 1972E and 1960F and the photometric calibration of Hill et al. (1998), leads to a Hubble constant of H0=68+/-2(random)+/-5(systematic) km/s/Mpc. Adopting the Kennicutt et al. (1998) Cepheid period-luminosity-metallicity dependency decreases the inferred H0 by 4%. The H0 result from Type Ia SNe is now in good agreement, to within their respective uncertainties, with that from the Tully-Fisher and surface brightness fluctuation relations.