The LIGO-Virgo-KAGRA Collaboration has announced on April 5 2024 the detection of a Gravitational Waves signal, called GW230529, coming from a coalescence of two compact objects observed in May 2023.

The heaviest astrophysical object involved in the coalescence has a mass between 2.5 and 4.5 solar masses at 90% probability. The nature of this component is uncertain as its mass is larger than the expected range for neutron stars and smaller than the expected range for black holes. Recent observations challenge the general expectation that no compact object would lie in the range between approximately 3 and 5 solar masses (also called the “mass gap”) and GW230529 is the first Gravitational Wave signal involving an object that lies with high probability in the mass gap.  The secondary component has a mass between 1.2 and 2.0 solar masses and is almost certainly a neutron star.

This is the first result released publicly from the LIGO-Virgo-KAGRA fourth observing run. On April 10th 2024 (after a two-months break) observation has resumed for the two LIGO detectors and the Virgo detector. With almost two years of accumulated data at the end of the observing run, many more interesting results are to come!

The GW IP2I group is on the front line of LIGO-Virgo-KAGRA searches for such signals, and has been directly involved in the detection of GW230529.

Read the science summary by LIGO-Virgo-KAGRA:

Read the preprint: