In A Historic Discovery, A Neutron Star Merger Has Been Observed For The Very First Time

Artist impression of neutron star merging after emitting gravitational waves. ESO/L. Calçada/M. Kornmesser

The source changed very quickly compared to other cosmic explosions. For example, it cooled off in just a couple of days, while supernovae might take weeks or months. The light observations were also able to show that merger created a lot of heavy elements. The mechanism for their production, called the r-process, require so much energy that only catastrophic events like a neutron star being destroyed could create them. And this seems to be the case.

If all this wasn’t enough pivotal science, researchers were also able to work out more about the final interaction. The merger produced a very narrow high-energy jet, which wouldn't normally be visible as it wasn't pointing at us, but after about 10 days the jet opened up and was observed in both X-ray and radio. We have never seen this moment before and it told the team a lot.

“It's an amazing amount of information on the merger itself,” Dr. Margutti confirmed.

The source has also shown that neutron star mergers can also be responsible for the emission of gamma-ray bursts. The Fermi telescope caught a gamma-ray emission at the same time as the GW signal, and the Swift observatory saw ultraviolet and optical light emission which was 1,000 times brighter than your typical nova. For decades, astronomers have hypothesized that neutron stars interacting were the cause behind such events and although this one is not exactly the classic GRB (it’s on the short-side) it tells us a lot about these events.

“Now for the first time, we're basically solving the mystery with gravitational waves. It’s a weird short gamma-ray burst. it’s a bit faint and it’s the closest we have seen by far. Is it typical? We don’t know. So, there are more questions marks there,” Dr Kalogera explained.

Of the five gravitational waves observed so far, GW170817 is the strongest observed yet. 

The two LIGO observatories in Louisiana and Washington and the VIRGO one in Italy are currently switched off and undergoing some tuning before being turned back on in late 2018. By then, events like this might soon become the norm for astrophysical observations. The age of gravitational and electromagnetic astronomy has now begun in full.

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