Curtin University and UWA leads observation of neutron star collision

Picture: LIGO Virgo
University of WA physics professors (l-r) Davis Coward, Li Ju and Linqing Wen say recording the neutron stars' collision has opened a new window to understanding the universe. Picture: Jon Bassett
Picture: LIGO Virgo University of WA physics professors (l-r) Davis Coward, Li Ju and Linqing Wen say recording the neutron stars' collision has opened a new window to understanding the universe. Picture: Jon Bassett

AN Australian network of astronomers – led by Curtin University’s Phil Bland – was the only facility on Earth to be looking in the right direction to observe a rare collision of two neutron stars.

A US observatory and a detector in Italy first realised the stars were going to merge in August, so Curtin’s Desert Fireball Network and the Murchison Widefield Array radio telescope joined in a global effort to record the event.

The observations were released in the US overnight.

Gravitational waves can be detected before the neutron stars merge, and more than 3000 astronomers pointed every available telescope in an attempt to capture the bursts of radiation.

“The Desert Fireball Network cameras that we have set up across Australia observe the whole sky, all night every night and in this case we got really lucky with one of our cameras in Western Australia in the right spot at the right time when the neutron stars went bang,” Professor Bland said.

A neutron star is formed when massive stars explode in supernovas.

They are the smallest, densest stars known to exist with one teaspoon of neutron star material weighing more than a billion tonnes.

This discovery marks the first time scientists have been able to detect both gravitational waves (ripples in space and time) and light from the collision of two neutron stars at the same time, with the results announced overnight in the US and published in the journal Physical Review Letters.

The scientists used the data observed to generate images of what they think the collision would look like.

UWA plays key role too

UWA physicists say their galaxy-sized collection of data is the real gold from recording the 120-million-year-old collision of two neutron stars.

“This is blue-sky science as it probes the fundamentals of our existence, like being able to monitor in detail the creation of heavy metals like gold,” Associate Professor of physics David Coward said.

The university announced its Zadco telescope in Gingin recorded the collision during four days from August 17.

The two previously Sun-sized stars had condensed to 10km-wide spheres before hitting and sending gravitational waves, gamma rays 1.7 seconds later, and light several hours afterwards, 120 light-years to Earth to be initially be detected by US and European scientists that day.

Thousands of scientists world-wide are now examining information form 70 telescopes measuring the waves and rays, light and radio signals that left the collision when dinosaurs ruled this planet.

Previously, scientists thought they would see a neutron star collision about once a year, but Prof Coward said having the world’s telescopes look at one for so many days would produce hundreds of scientific papers that could change the way life is viewed.

“The collisions also lead 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 new range of possibilities,” he said.

One of the first revelations was data indicating gravitational waves and light travelled at the same speed, in addition to proof recently-discovered gravitational waves exist with gamma rays.

“But to us the collision is definitely bigger than gravitational wave discovery because it opens multiple windows to the most exotic events in the universe,” Prof Coward said.

The Europe-based LIGO and Virgo gravitational wave detectors which initial detected the collision were only operating at 30 per cent sensitivity, and scientists now want to increase that capacity across the globe.

University of WA Professor of Physics Li Ju said having more of the devices could create a “golden era of gravitational wave astronomy” looking further back than 120 light-years for the star collisions creating life’s building blocks, but that meant spending “100s of millions”.

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