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Scientists from The University of Western Australia have helped usher in a new dawn of astronomy by assisting with the detection of one of the greatest phenomena ever witnessed in astronomy: the collision of two neutron stars 120 million light-years away.
On 17 August 2017 a burst of gravitational waves (ripples in space-time) was detected by the US and European gravitational wave detectors LIGO and Virgo. Within seconds, a burst of gamma rays was detected by NASA. Several hours later it emitted an optical glow, which was monitored by ground-based telescopes across the globe, including The University of Western Australia’s Zadko Telescope.
The Zadko Telescope, operated by UWA’s School of Physics and the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), monitored the explosion for four days. The data will be combined with other OzGrav observations to understand the exotic physics unfolding after the collision.
UWA’s Associate Professor David Coward said the discovery introduced a new type of astronomy called multi-messenger astronomy.
“Everything about this discovery is new. The fact that gravitational waves, gamma rays, light and radio signals are all coming from the same source is extraordinary,” Associate Professor Coward said. ] Neutron stars are the smallest and densest stars known to exist and occur when a star about the mass of the sun condenses into a volume the size of Rottnest Island.
In this instance, two neutron stars orbiting each other at near the speed of light collided, releasing a burst of gravitational waves, gamma rays, optical light and then a slowly revealing burst of radio waves.
Associate Professor Coward said the discovery would allow us to unlock the mysterious process of how heavy metals such as gold formed in the Universe.
“The gold we wear comes from the collision of neutron stars billions of years ago and the optical glow we recorded through the Zadko Telescope originated from this process. In millions of years this material could become part of a new star and a new solar system,” Professor Coward said.
“This also leads to the evolution of life because life requires certain elements which are created from stars, so witnessing an event like this could open up a whole range of possible theories.”
The announcement comes less than a month after the discovery of gravitational waves won the 2017 Nobel Prize for physics.
UWA and OzGrav researcher Dr Eric Howell said the joint detection of a gravitational wave signal with a gamma-ray burst was theorised but we had expected to wait many years before observing this first incredible event.
“For the first time, scientists have worked together with different technologies to study this phenomenon and combined their data to create a timeline of this amazing story,” Dr Howell said.
“By combing all this data, scientists will be able to test the fundamental laws of physics under the most extreme conditions.”
The Zadko Telescope operates in Gingin and offers a window to the “transient universe” – a universe filled with fleeting flashes of light originating from the most exotic phenomena in the cosmos.
James Zadko, UWA Zadko Telescope benefactor, said UWA’s role in the discovery would help uncover some of the deepest mysteries of the universe.
“Given the time the telescope has operated, this is an extraordinary achievement and can lead to the understanding of multiple theories waiting to be answered,” Mr Zadko said.
UWA’s Vice-Chancellor Professor Dawn Freshwater said the University was extremely proud of the part research staff had played in this monumental event.
“This is a very significant discovery and comes on the heels of the confirmation of the existence of gravitational waves in 2015,” Professor Freshwater said.
“It is rewarding to see UWA strongly involved in both discoveries and confirmation that this University is at the forefront of world class research.”
The UWA researchers are working at the frontier of the world-wide effort to detect gravitational waves and contribute directly to this Nobel Prize-winning endeavour.
In addition to Professor Coward's group, the Gravitational Wave Astronomy group led by Professor Linqing Wen is leading the development of one of the few fast search pipelines in the world that can detect gravitational waves from LIGO detector data within tens of seconds of the events.
The group independently verified the detection of this very first binary neutron star coalescence event.
The instrumentation group led by Chunnong Zhao, Ju, Li and David Blair is leading a world-class research to help develop advanced gravitational wave detector technology at the Gingin site. Several of their students were working directly at the LIGO detector site at the time of the discovery.
LIGO is funded by the NSF, and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,200 scientists and some 100 institutions from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration and the Australian collaboration OzGrav. Additional partners are listed at https://ligo.org/partners.php
David Stacey (UWA Media and Public Relations Manager) (+61 8) 6488 3229 / (+61 4) 32 637 716
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