UIB researchers participate in the detection of the most massive black hole merger to date.

PalmResearchers from the Gravity group at the University of the Balearic Islands (UIB) have participated in the detection of the merger that produced a final black hole with more than 225 times the mass of the Sun. The signal, designated GW231123, was observed during the fourth observing campaign (O4) of the LVK network on November 23, 2023.

The two black holes that merged were approximately 100 and 140 times the mass of the Sun. In addition to their large mass, both are spinning rapidly, making this signal uniquely challenging to interpret and suggesting the possibility of a complex formation history.

This discovery challenges our current understanding of black hole formation, as standard models of stellar evolution do not consider the existence of such massive objects.

According to the researchers, a plausible explanation is that the black holes that formed this binary system originated from previous mergers of smaller black holes, which would imply a more complex evolutionary process than previously thought.

To date, approximately 100 black hole mergers have been observed using gravitational waves. Until this new discovery, the most massive binary system was the source of the GW190521 signal, with a much lower total mass of "only" 140 times that of the Sun.

As with other key discoveries in gravitational-wave astronomy made over the past 10 years, the Gravitational Physics: Theory and Observation (Gravity) group at the University of the Balearic Islands has played an important role in this discovery and its astrophysical interpretation.

Specifically, the discovery was made by the LIGO-Virgo-KAGRA (LVK) collaboration, using the LIGO Hanford and Livingston observatories, which are funded by the US National Science Foundation (NSF).