MYSTERIOUS OBJECT MAY BE LIGHTEST BLACK HOLE EVER FOUND
Astronomers have spotted what might be the lowest mass black hole ever found. Believed to be 2.6 times the mass of the Sun, the object was detected on 14 August 2019 by scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO) in the US and the Virgo interferometer in Italy.
Black holes form when the largest stars go supernova and their cores collapse under their own gravity. Until now, the lightest known black hole was five solar masses (our Sun = one solar mass).
The object may turn out not to be a black hole. But even so, its discovery is still significant because it falls squarely into the ‘mass gap’, the unexplained interval between the lightest known black holes and heaviest neutron stars.
“The mass gap has been an interesting puzzle for decades and now we’ve detected an object that fits inside it,” said Dr Pedro Marronetti, of the US’s National Science Foundation, which funds LIGO. “That can’t be explained without defying our understanding of extremely dense matter or what we know about the evolution of stars.”
“It left the scientists scratching their heads as to the identity of the object”
Neutron stars are the remnants of stars that aren’t quite big enough to form black holes. They are tiny, typically less than 20 kilometres wide, but extremely dense; the heaviest known neutron star is 2.5 solar masses.
“We don’t know if this object is the heaviest known neutron star or the lightest known black hole, but either way it breaks a record,” said Prof Vicky Kalogera, one of the authors of the report announcing the discovery.
The record-breaking object was detected by the gravitational waves produced when it merged with another much larger object, estimated to be 23 solar masses, in an astronomical event designated GW190814. The waves rippled
