Gravitational waves help unravel mystery of gamma ray bursts in space

Issued: Thu, 10 May 2018 10:03:00 BST

The data collected during historic first detection of a binary neutron star collision is helping astrophysicists further unravel the mystery of gamma-ray bursts in space.

Gamma-ray bursts are extremely energetic cosmological events in which massive amounts of gamma-ray light, hundreds of times brighter than a supernova, are released. Each burst is released as a directional jet of charged particles which can last anywhere from a few milliseconds to several minutes.

The first gamma-ray bursts were observed in the 1960s, and astronomers now see evidence of them at least once a day. However, until recently, the origins of gamma-ray bursts remained uncertain.  

While scientists had for some time suspected that binary neutron star (BNS) collisions were the source of at least some gamma-ray bursts, it wasn’t until the LIGO and Virgo gravitational wave detectors observed a BNS collision for the first time in August 2017 that the hypothesis was confirmed.

As telescopes around the world turned towards the spot in the sky where the collision occurred, they were able to see ample evidence of an accompanying gamma-ray burst.

In a new paper published today in the Astrophysical Journal, researchers from the University of Glasgow, the Georgia Institute of Technology in the United States and Radboud University Nijmegen in the Netherlands discuss how they have used statistical analysis of gravitational wave data from LIGO and Virgo to help deepen understanding of gamma-ray bursts.

The paper’s lead author is Daniel Williams, of the University of Glasgow’s School of Physics and Astronomy.

Daniel said: “The metaphor we like to use to explain the work we’re doing is to liken our gravitational wave detectors to standing in a dark room while someone with a flashlight walks in circles around you, turning it on and off at random. The gravitational wave signals are like the click of the switch on the flashlight, and once you turn towards the sound, the cone of light from the flashlight is similar to the jet from a gamma-ray burst.

"We used statistical analysis of a year's worth of data from the LIGO detectors to help us to draw conclusions about how focussed the beam of high-energy gamma rays from binary neutron stars can be.

“It’s just one example of the new kinds of discoveries that gravitational wave astronomy allows, and we’re very much looking forward to seeing what else the data collected by LIGO and Virgo has to offer us in the future.

The team’s paper, titled ‘Constraints On Short, Hard Gamma-Ray Burst Beaming Angles From Gravitational Wave Observations’, is published in Astrophysical Journal. The research was supported by funding from the Science and Technology Facilities Council (STFC), the Netherlands Organization for Scientific Research and the National Science Foundation (NSF).

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