A study hints at the existence of the closest black holes to Earth in the Hyades star cluster

Paper published in the journal Monthly Notices of the Royal Astronomical Society This indicates that there are several black holes in the Hyades cluster – the closest open cluster to our solar system – making it the closest black hole to Earth ever discovered.

The study is the result of a collaboration between a group of scientists led by Stefano Torniamenti, of the University of Padua (Italy), with significant involvement with Mark Gillis, ICREA Professor in the Faculty of Physics of the University’s Institute for Cosmology. from Barcelona (ICCUB) and the Institute for Space Studies of Catalonia (IEEC), Friedrich Anders (ICCUB-IEEC).

Specifically, this result was found during a research residency of expert Stefano Torneamenti at ICCUB, one of the research units that make up the IEEC.

Black holes in the Hyades star cluster?

Since their discovery, black holes have been one of the most mysterious and fascinating phenomena in the universe, and have become a subject of study for researchers around the world. This is especially true of small black holes because they are observed during the detection of gravitational waves. Since the detection of the first gravitational waves in 2015, experts have observed several events that are consistent with the merger of pairs of low-mass black holes.

For the published study, a team of astrophysicists used simulations that track the motion and evolution of all the stars in Hyades – located at a distance of about 45 parsecs, or 150 light-years – to reproduce their current state.

Open clusters are loosely linked groups of hundreds of stars that share certain characteristics such as age and chemical properties. The simulation results were compared with the actual positions and velocities of the stars in Hyades, which are now known precisely from observations made by the European Space Agency (ESA) Gaia satellite.

“Our simulations can only simultaneously match the mass and size of Hyades if there are some black holes at the center of the cluster today (or even soon).” paper.

The observed properties of Hyades are best reproduced by simulations with two or three present-day black holes, although simulations in which all black holes were ejected (less than 150 million years ago, roughly the last quarter of the cluster’s life) ) is still able to give a good match, because the cluster’s evolution has not been able to erase the traces of the former black hole.

The new findings indicate that the black holes born in Hyades are still inside the cluster, or very close to the cluster. This makes them the closest black holes to the Sun, much closer than the previous candidate (Gaia BH1, 480 parsecs from the Sun).

In recent years, advances made by the Gaia space telescope have made it possible for the first time to study the position and velocity of open cluster stars in detail and to identify individual stars with confidence.

“This observation helps us understand how the presence of black holes affects the evolution of stellar clusters and how the stellar clusters, in turn, contribute to the sources of gravitational waves,” says Mark Giles, a member of the Department of Quantum Physics and Astrophysics at UCLA. First author in Barcelona. “These results also give us insight into how these mysterious objects are distributed across the galaxy.”