Measurements of the gravitational waves generated in the event were used to refine the Hubble constant. This occasion offered a brand new solution to measure the expansion rate of the Universe, identified by scientists as the Hubble Fixed. 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 main strategies of figuring out the Hubble Fixed use the characteristics of the Cosmic Microwave Background, the leftover radiation from the Big Bang, or a particular kind of supernova explosions, referred to as Kind Ia, within the distant Universe.
"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.
The technique is similar to the supernova explosions. The velocity divided by the distance gives the Hubble constant. The shape of the gravitational wave signal shows how "bright" the event should have been, against which observations of the event can be compared and its distance calculated.
When two massive neutron stars collide, they produce an explosion and an eruption of gravitational waves. Measuring the "brightness", or intensity of the gravitational waves as received at Earth can yield the distance. The intensity of the gravitational waves varies with their orientation in relation to the orbital plane of the two neutron stars. The gravitational waves are stronger and weaker in the direction perpendicular to the orbital plane when the orbital plane is up-edge from Earth.
Data to determine the orientation of the merger is needed for this calculation, in this case provided by an ultra high resolution radio imaging of the fireball of material emitted as the stars merged.
Over a period of months, astronomers used the radio telescopes to measure the movement of a superfast beam of material ejected by the explosion. "We used these measurements together with detailed hydrodynamic simulations to determine the orientation angle so that we could use the gravitational waves to determine the distance", says Ehud Nakar of Tel Aviv University.
However, there is a twist to using neutron star mergers to measure the universe's expansion.
"We think that 15 more such events that can be observed both with gravitational waves and in great detail with radio telescopes, may be able to solve the problem", said Kenta Hotokezaka, of Princeton University.
The results of the team's research has been published today in Nature Astronomy.