Black Hole, Black Hole Collision

In a remarkable discovery, a team of researchers has detected the biggest known black hole collision via the ripples, known as gravitational waves; it formed in space-time. Though the existence of the gravitational waves was predicted by Theoretical physicist Albert Einstein nearly a century ago, it was in the year 2016 that the researchers discovered the gravitational waves in a breakthrough.

The collision of two black holes is believed to be the reason behind the formation of an all-new black hole which is around 80 times bigger than our Sun. The Australian National University (ANU) worked in collaboration with the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) to form a team of researchers to carry out the study.

The team has discovered this as well as three other black hole collisions in total by re-evaluating the data captured in the first two observing runs carried out by Advanced LIGO, informed Susan Scott, an ANU professor and lead researcher of the study. It was in July last year that the event of a merger of two separate black hole binary system was detected by the researchers which led to the formation of a third black hole, the biggest one ever known.

The event took place far off, around 9 billion light-years away. This is also the event where black holes were observed to be spinning at the highest speed out of all the mergers which have been observed until now. Besides, it is also the most faraway merger to have been observed to date, said Scott.

The team of researchers released computer calculations showcasing the ripples or gravitational waves they noticed and also black holes which discharged waves. It is currently being believed by the Astrophysicists that there are nearly ten thousand black holes in our Milky Way’s centre, with a ginormous black hole present in their core.

On the other hand, ANU detected the three other small black hole collisions last year, between 9th and 23rd of August. These three collisions occurred around 3-6 billion light-years away and were supermassive in size, thus producing black holes which were 56-66 times as big as our Sun. The three black holes formed as a result of four black hole binary systems colliding into one another and emitting strong ripples in space said, Scott.

Such black-hole collision detections also help get a better understanding as to how many black holes exist in our universe and also determine the range of such large masses, he added. It will also help observe how fast the black holes spin when there’s fusion. The researchers plan on to improve the ripples detectors continually to facilitate better detection of cataclysmic events taking place far off in the space.

After the initial observations were detected, the team recalibrated the detector while the data it recorded was cleaned up to conduct the next observation. This process helped increase the detector’s network sensitivity thus facilitating the researchers to observe more sources, said Scott. The researchers in their study have included the enhanced models of the anticipated signals.

With the second black hole observing run getting over in August 2017, the researchers have continued to upgrade the Virgo and LIGO ripples detectors to make these even more sensitive. LIGO’s two ripples detectors in Hanford, as well as Livingston and Virgo’s ripples detector near Pisa, are expected to be upgraded until 2019’s spring.

The changes and improvements made to the detectors may result in an increased number of ripples sightings. This implies that in the upcoming third black hole observing run, which will begin early in 2019, the researchers will be able to detect the events which take place further out in the universe. This means some detections and ripples from new as well as unknown sources in the space, said Scott.

The international team of researchers has observed ripples or gravitational waves emitted by ten distinct black hole fusions as well as a neutron star collision in the last three years. The neutron stars are known as the densest form of stars present in our universe. They have a diameter of around 20 kilometres.

The research team led by Scott is also currently in the process of developing an all-new project which will help them detect the ripples radiating from a neutron star fusion. Postdoctoral fellow in the team, Karl Wette said that the researchers were unsure what developed as a result of the fusion of neutron stars which was observed last year in August. It may be a neutron star which turned into a black hole immediately or over some time, said Wette.

The new project by the researchers will help them gain critical information from the neutron-star fusion. The discoveries and results will be presented at Australian Institute of Physics Congress in the latter half of December. The study results are expected to appear in the journal ‘Physical Review X’ soon.


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