In an article in the Sydney Morning Herald today, Marcus Strom reports
on the reduction in uncertainty in the measurement of the local
Hubble constant.
The implication of the refined value is that at least locally the universe is
expanding at a rate faster than previously estimated.
Article here -
http://www.smh.com.au/technology/sci...02-gpa1os.html
Quote:
|
Originally Posted by Riess et. al. A 2.4% Determination of the Local Value of the Hubble Constant
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 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 NGC4258 have been observed with WFC3
in the optical and near-infrared, 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 NGC4258, 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.
|
Paper here -
https://arxiv.org/pdf/1604.01424.pdf
