The Megamaser Cosmology Project. XIII. Combined Hubble Constant Constraints

Published

Journal Article

© 2020. The American Astronomical Society. All rights reserved.. We present a measurement of the Hubble constant made using geometric distance measurements to megamaser-hosting galaxies. We have applied an improved approach for fitting maser data and obtained better distance estimates for four galaxies previously published by the Megamaser Cosmology Project: UGC 3789, NGC 6264, NGC 6323, and NGC 5765b. Combining these updated distance measurements with those for the maser galaxies CGCG 074-064 and NGC 4258, and assuming a fixed velocity uncertainty of 250 km s-1 associated with peculiar motions, we constrain the Hubble constant to be H 0 = 73.9 ± 3.0 km s-1 Mpc-1 independent of distance ladders and the cosmic microwave background. This best value relies solely on maser-based distance and velocity measurements, and it does not use any peculiar velocity corrections. Different approaches for correcting peculiar velocities do not modify H 0 by more than ±1σ, with the full range of best-fit Hubble constant values spanning 71.8-76.9 km s-1 Mpc-1. We corroborate prior indications that the local value of H 0 exceeds the early-universe value, with a confidence level varying from 95% to 99% for different treatments of the peculiar velocities.

Full Text

Duke Authors

Cited Authors

  • Pesce, DW; Braatz, JA; Reid, MJ; Riess, AG; Scolnic, D; Condon, JJ; Gao, F; Henkel, C; Impellizzeri, CMV; Kuo, CY; Lo, KY

Published Date

  • March 1, 2020

Published In

Volume / Issue

  • 891 / 1

Electronic International Standard Serial Number (EISSN)

  • 2041-8213

International Standard Serial Number (ISSN)

  • 2041-8205

Digital Object Identifier (DOI)

  • 10.3847/2041-8213/ab75f0

Citation Source

  • Scopus