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A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT

Publication ,  Journal Article
Riess, AG; Macri, LM; Hoffmann, SL; Scolnic, D; Casertano, S; Filippenko, AV; Tucker, BE; Reid, MJ; Jones, DO; Silverman, JM; Chornock, R ...
Published in: Astrophysical Journal
July 20, 2016

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 3.4σ 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 2.1σ 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 ΔN 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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Published In

Astrophysical Journal

DOI

EISSN

1538-4357

ISSN

0004-637X

Publication Date

July 20, 2016

Volume

826

Issue

1

Related Subject Headings

  • Astronomy & Astrophysics
  • 5109 Space sciences
  • 5107 Particle and high energy physics
  • 5101 Astronomical sciences
  • 0306 Physical Chemistry (incl. Structural)
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
  • 0201 Astronomical and Space Sciences
 

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Riess, A. G., Macri, L. M., Hoffmann, S. L., Scolnic, D., Casertano, S., Filippenko, A. V., … Foley, R. J. (2016). A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT. Astrophysical Journal, 826(1). https://doi.org/10.3847/0004-637X/826/1/56
Riess, A. G., L. M. Macri, S. L. Hoffmann, D. Scolnic, S. Casertano, A. V. Filippenko, B. E. Tucker, et al. “A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT.” Astrophysical Journal 826, no. 1 (July 20, 2016). https://doi.org/10.3847/0004-637X/826/1/56.
Riess AG, Macri LM, Hoffmann SL, Scolnic D, Casertano S, Filippenko AV, et al. A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT. Astrophysical Journal. 2016 Jul 20;826(1).
Riess, A. G., et al. “A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT.” Astrophysical Journal, vol. 826, no. 1, July 2016. Scopus, doi:10.3847/0004-637X/826/1/56.
Riess AG, Macri LM, Hoffmann SL, Scolnic D, Casertano S, Filippenko AV, Tucker BE, Reid MJ, Jones DO, Silverman JM, Chornock R, Challis P, Yuan W, Brown PJ, Foley RJ. A 2.4% DETERMINATION of the LOCAL VALUE of the HUBBLE CONSTANT. Astrophysical Journal. 2016 Jul 20;826(1).
Journal cover image

Published In

Astrophysical Journal

DOI

EISSN

1538-4357

ISSN

0004-637X

Publication Date

July 20, 2016

Volume

826

Issue

1

Related Subject Headings

  • Astronomy & Astrophysics
  • 5109 Space sciences
  • 5107 Particle and high energy physics
  • 5101 Astronomical sciences
  • 0306 Physical Chemistry (incl. Structural)
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
  • 0201 Astronomical and Space Sciences