Gravitational waves show the lightest black hole ever observed

Gravitational-wave detectors discovered a cosmic collision in which a giant black hole swallowed a mysterious object that seemed too heavy to be a neutron star, but too light to be a black hole.

Weighing 2.6 times the mass of the Sun, the object falls into a hypothetical “mass gap” – the segment between the heaviest neutron star and the lightest black hole that some theories predict. “People who thought there was a so-called mass gap would probably have to rethink it,” says Cole Miller, an astrophysicist at the University of Maryland.

The data was obtained from physicists working with the laser interferometric gravitational-wave observatory (LIGO), a pair of detectors in Louisiana and Washington, and with a similar Virgo detector in Italy. Both centers found the fusion of objects with masses 23 and 2.6 times greater than that of the Sun.

According to Vicky Kalogera, an astrophysicist and team member at Northwestern University, a 2.6-solar object with astonishment is probably the lightest black hole that has ever been seen.