Astronomers discover most massive stellar black hole in our galaxy

Delving deep into data from the European Space Agency's Gaia mission, scientists have uncovered a sleeping giant - a monster black hole hiding in the constellation Aquila, less than 2000 light-years from Earth.

With a mass of about 33 times that of the Sun, Gaia BH3 is the heaviest black hole of stellar origin discovered in our galaxy. To put this into perspective, the typical mass of stellar black holes known within the Milky Way is around 10 solar masses.

Previously, the record for the most massive black hole was held by Cyg X-1, an X-ray binary located in the constellation Cygnus, with an estimated mass of about 20 solar masses.

Looking through data from the @ESAGaia mission, scientists have uncovered a ‘sleeping giant’: a large black hole, 33 times the mass of our Sun, hiding less than 2000 light-years from Earth. This is the first time a black hole of stellar origin this big has been spotted in our… pic.twitter.com/GDDEVLWIkB

— European Space Agency (@esa) April 16, 2024

An ancient giant star that formed in the first two billion years after the Big Bang orbits Gaia BH3 at about 16 times the Sun-Earth distance. This is rather uncommon because at that time our galaxy started to assemble.

The star is a part of the Galactic stellar halo and is moving in the opposite direction to the stars of the Galactic disc. Its trajectory suggests that it was probably part of a small galaxy, or a globular cluster, engulfed by our own galaxy more than eight billion years ago.

Gaia BH3 was discovered when the Gaia collaboration was analysing the preliminary data in preparation for the fourth release of the Gaia catalogue. The next data release from Gaia promises to reveal more about binary systems and potentially uncover more dormant black holes in our galaxy.