Virgo and LIGO spot a mystery object merging with a black hole

Virgo and LIGO have announced the discovery of a compact object of about 2.6 solar masses, placing it in a range between the heaviest neutron star and the lightest black hole ever seen. About 800 million years ago, this object merged with a black hole of 23 solar masses and, in so doing, emitted an intense gravitational wave. Since the observation of this wave alone, which was detected on Earth in August 2019, does not allow us to distinguish whether the compact object is a black hole or a neutron star, its precise nature remains a mystery.

See the whole press release