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A research team led by astronomers from the University of Warwick had to wait over 100 days to see the first of the star neutrons to merge to form back behind the sun's glare.
They were rewarded with the first confirmed visual observation of a stream of material that was still coming out of the fused star exactly 110 days after the first observation of the first cataclysmic fusion. Their observations confirm a key prediction on the consequences of neutron star mergers
The fusion of the GW170817 binary neutron stars occurred at 130 million light-years in a galaxy named NGC 4993. It was detected in August 2017 by the advanced laser interferometer. Observatory (Adv-LIGO) and Gamma Ray Burst (GRB) observations, then became the first fusion of neutron stars to be observed and confirmed by visual astronomy.
After a few weeks, the fused star then passed behind the glare of our sun leaving it effectively hidden from the astronomers until it disappeared from this glare 100 days later the melting event. It was at this point that the research team of the University of Warwick was able to use the Hubble Space Telescope to see that the star was still producing a powerful beam of light in a direction that , although distant from the Earth, was beginning to spread
Their research has just been published in an article titled: "Optical remanence of the short burst of gamma rays associated with GW170817" in the site of Nature Astronomy at 16h, British time, Monday. July 02, 2018.
The lead author of the article, Dr. Joe Lyman from the Department of Physics of the University of Warwick, said:
"At first we saw the visible light fed by the radioactive decay of heavy elements, on a hundred days later and this disappeared, but now we see a jet of material, ejected at an angle from us, but almost at the speed of light , which is very different from what some have suggested, that the material would not come in a jet, but in all directions. "
Professor An Levan of the Department of Physics of the University of Warwick, a Other authors' main authors added:
"If we had looked straight down this beam, we would have seen a very strong explosion of gamma rays.That means it's very likely that every neutron star that merges actually creates an explosion of gamma rays a, but we only see a small fraction of them because the jet does not align so often. Gravitational waves are a whole new way to find this kind of event, and they might be more common than we think. "
These observations confirm the prediction made by the second author of the paper, Dr. Gavin Lamb of the University of Leicester's Department of Physics and Astronomy said that these types of events will reveal the structure of these jets of materials traveling near the speed of light:
"The light behavior of these jets, how it illuminates be used to determine the speed of the material throughout the jet. As the reverb shines, we look deeper into the jet structure and probe the faster components. This will help us understand how these streams of matter, traveling near the speed of light, form and how they are accelerated at these phenomenal speeds. "
Learn more:
Signals of a spectacular fusion of neutron stars that made gravitational waves slowly fade
More information:
The optical remanence of the short gamma burst associated with GW170817, Nature Astronomy (2018). DOI: 10.1038 / s41550-018-0511-3, https://www.nature.com/articles/s41550-018-0511-3
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