NRAO: New Method for Measuring Universe's Expansion
Posted: Mon Jul 08, 2019 7:22 pm
New Method May Resolve Difficulty in Measuring Universe's Expansion
National Radio Astronomy Observatory | 2019 Jul 08
A Hubble Constant Measurement from Superluminal Motion of the Jet in GW170817 ~ Kenta Hotokezaka et al
National Radio Astronomy Observatory | 2019 Jul 08
Astronomers using National Science Foundation (NSF) radio telescopes have demonstrated how a combination of gravitational-wave and radio observations, along with theoretical modeling, can turn the mergers of pairs of neutron stars into a “cosmic ruler” capable of measuring the expansion of the Universe and resolving an outstanding question over its rate.
The astronomers used the NSF’s Very Long Baseline Array (VLBA), the Karl G. Jansky Very Large Array (VLA) and the Robert C. Byrd Green Bank Telescope (GBT) to study the aftermath of the collision of two neutron stars that produced gravitational waves detected in 2017. This event offered a new way to measure the expansion rate of the Universe, known by scientists as the Hubble Constant. The expansion rate of the Universe can be used to determine its size and age, as well as serve as an essential tool for interpreting observations of objects elsewhere in the Universe.
Two leading methods of determining the Hubble Constant use the characteristics of the Cosmic Microwave Background, the leftover radiation from the Big Bang, or a specific type of supernova explosions, called Type Ia, in the distant Universe. However, these two methods give different results.
“The neutron star merger gives us a new way of measuring the Hubble Constant, and hopefully of resolving the problem,” said Kunal Mooley, of the National Radio Astronomy Observatory (NRAO) and Caltech. ...
A Hubble Constant Measurement from Superluminal Motion of the Jet in GW170817 ~ Kenta Hotokezaka et al
- Nature Astronomy (online 08 Jul 2019) DOI: 10.1038/s41550-019-0820-1
- arXiv.org > astro-ph > arXiv:1806.10596 > 27 Jun 2018 (v1), 29 Jun 2018 (v2)