Gravitational wave scientists announce collision of neutron stars

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Optical telescopes picked up the radioactive glow of these heavy elements - strong evidence, scientists say, that neutron-star collisions produce much of the universe's supply of heavy elements like gold. Neutron stars are the second densest known objects in the universe after black holes, and both form under similar circumstances.

The discovery, published Monday in the journal Physical Review Letters, was made possible by the massive, laser-based gravitational wave detectors first envisioned by MIT physicist Rainer Weiss half a century ago and by an worldwide network of partner observatories that responded by quickly aiming telescopes and scanning the night sky in search of the light and other electromagnetic radiation that shot across space from the same collision that emitted the gravitational waves. "It is a triumph for the theorists, a confirmation that the LIGO-Virgo events are absolutely real, and an achievement for ESO to have gathered such an astonishing data set on the kilonova".

Dr Joe Lyman, from the University of Warwick, said: "The exquisite observations obtained in a few days showed we were observing a kilonova, an object whose light is powered by extreme nuclear reactions".

The discovery was made using the US -based Laser Interferometer Gravitational-Wave Observatory (LIGO); the Europe-based Virgo detector; and some 60 ground- and space-based telescopes. Two seconds later, the Fermi space telescope measured a burst of high-energy radiation from the explosion.

LIGO scientists held their first press conference in February 2016 to announce the first detection of a gravitational wave.

Now, telescopes have spotted evidence for newly-synthesised heavy elements in the light bursts from one such cataclysmic crash.

Before the night was out, a number of different observatories had picked up a new twinkle in the sky.

Astronomers witnessed the collision of two neutron stars in a distant galaxy located 130 million light years from Earth.

Over subsequent weeks, an extensive observation campaign using a variety of instruments was mounted around the globe and in space to try to learn more about what had caused the new pinpoint of light. A neutron star is the remnant of a larger star whose core has collapsed.

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"We're going to have a lot more to do moving forward", said Kalogera. Comparing the gravitational-wave signal with the redshift, or stretching, of the electromagnetic signals offers a new way of measuring the so-called Hubble constant, which gives the age and expansion rate of the universe.

This observation is hugely important as it has enabled scientists to prove for the first time where some heavy metals on Earth come from. The astronomers also obtained the earliest spectra of the collision, which may allow them to explain how numerous universe's heavy elements were created-a decades old question for astrophysicists. Each of these bands of the electromagnetic spectrum yields different kinds of information about the source, allowing the researchers to study this neutron-star collision in unprecedented detail.

Astronomers, including a team at Cal State Fullerton, have detected two neutron stars merging together, proving for the second time in two years a key element of Albert Einstein's theories about the universe. I expect it will be remembered as one of the most studied astrophysical events in history.

The left image is from 11 hours after the LIGO/Virgo detection of the gravitational wave source. But what about the heavier ones like gold, platinum and uranium? A teaspoon of neutron star would weigh as much as one billion tons.

"It's now clear that binary neutron stars are a source of the short gamma ray bursts", though there may be other origins too.

While Professor Lorraine Hanlon from UCD School of Physics worked on research looking at the detection of the gamma-ray burst by the INTEGRAL satellite.

"From informing detailed models of the inner workings of neutron stars and the emissions they produce, to more fundamental physics such as general relativity, this event is just so rich", said David Shoemaker, head of the Ligo collaboration that helped detect the celestial smashup.

Scientists have described the findings as "astonishing", one of the "biggest astronomical discoveries of the century so far", and an "incredible feat in technology" some 40 years after gravity waves from black holes were first detected.

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