Mystery object bridges black hole gap
Is it the heaviest neutron star or the lightest black hole?
A ripple in space time has allowed astronomers to discover a rare object that bridges the gap between black holes and neutron stars, a recent report has announced. The find could give astronomers insight into how these dense objects form.
Black holes and neutron stars are both incredibly dense objects created during the deaths of the Universe’s largest stars. Which one forms depends on the mass of the dying star, with black holes arising from the largest. Over the years, astronomers have found no neutron stars heavier than 2.5 solar masses, while the lightest black hole discovered is 5 solar masses, leaving a ‘mass-gap’ where no objects seem to exist, until recently.
Last summer, astronomers at the LIGO and Virgo interferometer observatories were searching for gravitational waves, ripples in space time created by the merging of large objects. On 14 August 2019, they detected a wave from a 23 solar-mass black hole merging with an object of 2.6 solar masses.
“The reason these findings are so exciting is because we’ve never detected an object with a mass firmly inside the theoretical mass gap between neutron stars and black holes before,” says Laura Nuttall from the University of Portsmouth, part of the LIGO-Virgo team. “Is it the lightest black hole or the heaviest neutron star we’ve ever seen?”
The merger is also exciting for the big difference in the masses of the pair, larger than any other merging system that has been observed to date. The discrepancy is making astronomers reassess their theories about how black holes pair up before merging together. www.ligo.caltech.edu