Scientists have detected gravitational waves originating from the biggest known black hole collision in the universe. Occurring about nine billion years ago, it led to the formation of a new black hole about 80 times larger than the Sun.
The infinitesimally tiny ripples resulting from the collision travelled at the speed of light, but only reached Earth for the first time in July 2017, scientists claimed.
Later in August 2017, scientists detected three other gravitational waves originating from the merger of other small black holes.
All these four separate events were discovered after scientists re-analysed data from the Advanced LIGO's first two observing runs. Twin LIGO observatories sit about 3,000 kilometres apart in Livingston, Louisiana; and Hanford, Washington in the US.
After the initial observational runs were completed, scientists recalibrated the data, which increased the sensitivity of the detector network and enabled the scientists to detect more sources. They also used data from the Italian Virgo gravitational wave detector, in combination with LIGO's observations, to precisely calculate the sources in the sky.
The collision that led to formation of the biggest known black hole was detected on 29 July 2017.
"This event also had black holes spinning the fastest of all mergers observed so far. It is also by far the most distant merger observed," said Professor Susan Scott, the leader of the General Relativity Theory and Data Analysis Group at ANU and a chief investigator with the Centre of Excellence for Gravitational Wave Discovery, funded by the Australian Research Council.
The other three black hole mergers were detected between 9 and 23 August 2017. They happened between three and six billion light years away, and led to formation of black holes about 56 to 66 times bigger than the Sun.
In the past three years, scientists have detected gravitational waves on 11 separate instances - 10 originating from different black hole mergers (the first detection reported in 2016) and one coming from neutron star collision.
Professor Scott says that the detection of these events will help improve our current understanding of the number of black holes in the universe, their masses and their spinning speed during a merger.
The detailed findings of the research will be published in the journal Physical Review X.
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