Indian scientists decode gravitational wave mystery

An Indo-US team of astronomers have decoded a mystery behind the most powerful gravitational wave detected so far.

The discovery not only opened up a new window to look at the rare cosmic phenomenon, but also challenged an established theory, used to explain such events.

A couple of months ago, the most powerful gravity wave, produced during a violent collision of two massively dense stars, known as neutron stars, was discovered.

The strongest GW signal came from the smash-up of two neutron stars that are so heavy that a tea spoon-full of neutron star material weighs more than the Mount Everest.

Now another group of scientists comprising several Indian astronomers provided a new insight into this violent celestial collision.

Analysing the gravity and electromagnetic signals emitted from the merger, they showed a super-fast energy jet, launched from the two neutron stars as they collided, was slamming into the surrounding material and created a slower-moving, billowy cocoon.

Only two special detectors in the USA and Europe captured the gravity wave signals, but several other telescopes from around the world, including India's Giant Metrewave Radio Telescope near Pune, picked up the electromagnetic signals in various frequencies.

"For the first time gravitational waves from neutron star merger have been detected, and for the first time electromagnetic counterpart from this merger has been detected. In this historical feat, GMRT has the credit to detect it at the lowest frequency ever! It is a proud moment for Indian astronomy," said Poonam Chandra, astronomer at the National Centre for Radio Astrophysics, Pune who is part of the team.

The scientists got the clues from the radio signals. The radio emission-originally detected 16 days after the August 17 event and still measurable and increasing in strength as of December 2-tells a different story.

If the jet had been fast and beam-like, the radio light would have weakened with time, as the jet lost energy. The fact that the brightness of the radio light is increasing, suggests the presence of a cocoon that is choking the jet. "It's like the jet was fogged out," says Kunal Mooley, another team member from Caltech.

Gravity waves are a type of esoteric cosmic wave, whose existence was predicted by Albert Einstein more than a century ago, but the first one was detected only in September 2015.