For the first time, astronomers have detected gravitational waves from a merged, hyper-massive neutron star. The scientists, Maurice van Putten of Sejong University in South Korea, and Massimo della Valle of the Osservatorio Astronomico de Capodimonte in Italy, publish their results in Monthly Notices of the Royal Astronomical Society: Letters.

Gravitational waves were predicted by Albert Einstein in his General Theory of Relativity in 1915. The waves are disturbances in space-time generated by rapidly moving masses, which propagate out from the source.

By the time the waves reach Earth, they are incredibly weak and their detection requires extremely sensitive equipment. It took scientists until 2016 to announce the first observation of gravitational waves using the Laser Interferometer Gravitational Wave Observatory (LIGO) detector.

Since that seminal result, gravitational waves have been detected on a further six occasions. One of these, GW170817, resulted from the merger of two stellar remnants known as neutron stars. These objects form after stars much more massive than the Sun explode as supernovae, leaving behind a core of material packed to extraordinary densities.

At the same time as the burst of gravitational waves from the merger, observatories detected emission in gamma rays, X-rays, ultraviolet, visible light, infrared and radio waves - an unprecedented observing campaign that confirmed the location and nature of the source.

The initial observations of GW170817 suggested that the two neutron stars merged into a black hole, an object with a gravitational field so powerful that not even light can travel quickly enough to escape its grasp. Van Putten and della Valle set out to check this, using a novel technique to analyze the data from LIGO and the Virgo gravitational wave detector sited in Italy.

Their detailed analysis shows the H1 and L1 detectors in LIGO, which are separated by more than 3,000 kilometers, simultaneously picked up a descending 'chirp' lasting around 5 seconds.

Significantly, this chirp started between the end of the initial burst of gravitational waves and a subsequent burst of gamma rays. Its low frequency (less than 1 KHz, reducing to 49 Hz) suggests the merged object spun down to instead become a larger neutron star, rather than a black hole.

There are other objects like this, with their total mass matching known neutron star binary pairs. But van Putten and della Valle have now confirmed their origin.

Van Putten comments: "We're still very much in the pioneering era of gravitational wave astronomy. So it pays to look at data in detail. For us this really paid off, and we've been able to confirm that two neutron stars merged to form a larger one."

Gravitational wave astronomy, and eking out the data from every detection, will take another step forward next year when the Japanese Kamioka Gravitational Wave Detector (KAGRA) comes online.

Research Report: "Observational Evidence for Extended Emission to GW170817," Maurice H. P. M. van Putten and Massimo Della Valle, 2018 Sep. 4, Monthly Notices of the Royal Astronomical Society: Letters

Related Links
Royal Astronomical Society
Stellar Chemistry, The Universe And All Within It

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

SOFIA unravels the mysterious formation of star clusters
Moffett Field CA (SPX) Nov 12, 2018
The sun, like all stars, was born in a giant cold cloud of molecular gas and dust. It may have had dozens or even hundreds of stellar siblings - a star cluster - but these early companions are now scattered throughout our Milky Way galaxy. Although the remnants of this particular creation event have long since dispersed, the process of star birth continues today within our galaxy and beyond. Star clusters are conceived in the hearts of optically dark clouds where the early phases of formation have histo ... read more