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Scientists ponder over discovery of ‘physically impossible’ black hole

Scientists are analysing the gravitational-wave signals provided by LIGO and Virgo interferometer that provide details of a giant black hole which is so huge that until now has been thought to be physically impossible. So far, they have refused to confirm or deny the detection.

By: Tech Desk | New Delhi | Updated: September 5, 2019 8:32:04 am
black hole, giant black hole, giant black hole discovered that should not exist, physically impossible black hole Fundamentals of physics about how black holes form at stake. (Representational Image: Getty/Thinkstock)

Space scientists are analysing the signals provided by Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo interferometer that provide details of a big black hole which is so huge that until now has been thought to be physically impossible. However, so far, scientists from LIGO and Virgo have refused to confirm or deny the detection of the giant black hole, Quanta Magazine reported.

“The prediction is no black holes, not even a few” in this mass range, the report said quoting Stan Woosley, an astrophysicist at the University of California. “But of course we know nature often finds a way,”

A black hole is uninhabitable chasms of spacetime that end in a ‘singularity,’ or a mass of infinite density. It is a place so bleak that even the laws of physics break down there. Black holes have such powerful gravitational acceleration that even light cannot escape it.

However, in 1967, three physicists at the Hebrew University in Jerusalem realised that the core of a dying star will not collapse gravitationally into a black hole. Instead of this, that star will be undergoing a “pair-instability” supernova – an explosion that completely annihilates it in a matter of seconds, without leaving anything behind.

“The star is completely dispersed into space,” the Quanta report said citing the three physicists.

A pair-instability supernova takes place when the core grows so hot that light begins to spontaneously transform into electron-positron pairs.

The light’s radiation pressure had kept the star’s core intact; when the light transforms into matter, the resulting pressure drop causes the core to rapidly shrink and become even hotter, further accelerating pair production and triggering a runaway effect.

Eventually, the core becomes so hot that oxygen ignites that completely reverses the implosion of the core to an explosion. For the cores having a mass between about 65 and 130 times that of the Sun, will likely see the star get completely destroyed.

Cores between about 50 and 65 solar masses pulsate, shedding mass in successive explosions until they drop below the range where pair-instability takes place. This suggests that there should be no black holes with masses in the 50-to-130-solar-mass range, the report said.

Black holes can exist weighing in at more than 130 solar masses because the runaway implosion of such heavy stellar cores cannot be stopped, instead, they continue to collapse and form black holes.

However, since stars shed mass throughout their lives, a star would require to be born weighing at least 300 suns in order to end up as a 130-solar-mass core, and such huge stars are rare. Because of this reason, most of the experts assumed that the size of the black hole detected by LIGO and Virgo would be at around 50 solar masses, which is the lower end of the mass gap.

The million and billion-solar-mass supermassive black holes which anchor galaxies’ centers formed in a different way in the early universe. LIGO and Virgo are mechanically incapable of detecting the collisions of such supermassive black holes.

A gravitational wave detection is speculated to be the result of a cosmic collision involving a black hole of extraordinary size — reportedly as heavy as 100 suns.

Also Read | Supermassive black hole in our galaxy’s centre suddenly turned 75 times brighter

Last month, a black hole swallowing a neutron star was detected for the first time, through a violent event was detected by LIGO and Virgo.

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