Статья

A 2.4% DETERMINATION OF THE LOCAL VALUE OF THE HUBBLE CONSTANT<sup>*</sup>

Adam G. RiessDepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA;Lucas M. MacriGeorge P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station, TX, USASamantha L. HoffmannGeorge P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station, TX, USADan ScolnicDepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA;Stefano CasertanoSpace Telescope Science Institute, Baltimore, MD, USAAlexei V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA, USABrad E. TuckerDepartment of Astronomy, University of California, Berkeley, CA, USAMark J. ReidHarvard-Smithsonian Center for Astrophysics, Cambridge, MA, USADavid O. JonesDepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA;Jeffrey M. SilvermanDepartment of Astronomy, University of Texas, Austin, TX, USARyan ChornockAstrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH, USAPeter ChallisHarvard-Smithsonian Center for Astrophysics, Cambridge, MA, USAWenlong YuanGeorge P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station, TX, USAPeter J. BrownGeorge P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station, TX, USARyan J. FoleyDepartment of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL, USA

2016en

ABI

Аннотация

ABSTRACT We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%. The bulk of this improvement comes from new near-infrared (NIR) observations of Cepheid variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these in turn leverage the magnitude-redshift relation based on ∼300 SNe Ia at z < 0.15. All 19 hosts as well as the megamaser system NGC 4258 have been observed with WFC3 in the optical and NIR, thus nullifying cross-instrument zeropoint errors in the relative distance estimates from Cepheids. Other noteworthy improvements include a 33% reduction in the systematic uncertainty in the maser distance to NGC 4258, a larger sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of Cepheids in M31, and new HST -based trigonometric parallaxes for Milky Way (MW) Cepheids. We consider four geometric distance calibrations of Cepheids: (i) megamasers in NGC 4258, (ii) 8 DEBs in the LMC, (iii) 15 MW Cepheids with parallaxes measured with HST /FGS, HST /WFC3 spatial scanning and/or Hipparcos , and (iv) 2 DEBs in M31. The Hubble constant from each is 72.25 ± 2.51, 72.04 ± 2.67, 76.18 ± 2.37, and 74.50 ± 3.27 km s −1 Mpc −1 , respectively. Our best estimate of H 0 = 73.24 ± 1.74 km s −1 Mpc −1 combines the anchors NGC 4258, MW, and LMC, yielding a 2.4% determination (all quoted uncertainties include fully propagated statistical and systematic components). This value is 3.4 σ higher than 66.93 ± 0.62 km s −1 Mpc −1 predicted by ΛCDM with 3 neutrino flavors having a mass of 0.06 eV and the new Planck data, but the discrepancy reduces to 2.1 σ relative to the prediction of 69.3 ± 0.7 km s −1 Mpc −1 based on the comparably precise combination of WMAP +ACT+SPT+BAO observations, suggesting that systematic uncertainties in CMB radiation measurements may play a role in the tension. If we take the conflict between Planck high-redshift measurements and our local determination of H 0 at face value, one plausible explanation could involve an additional source of dark radiation in the early universe in the range of Δ N eff ≈ 0.4–1. We anticipate further significant improvements in H 0 from upcoming parallax measurements of long-period MW Cepheids.

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Идентификаторы

DOI: 10.3847/0004-637x/826/1/56

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