Gaia BH3, this is unheard of in our galaxy. And Gaia BH3 is the black hole with a record mass (33 times that of the Sun) which has just been spotted in our Milky Way.
Located 2,000 light years from Earth, in the constellation Eagle, the object belongs to the family of stellar black holes which result from the collapse of massive stars at the end of their lives. They are incomparably smaller than the supermassive black holes housed in the hearts of galaxies, the formation scenario of which is not known.
It was “by chance” that Gaia BH3 was discovered by the European Gaia space telescope, says Pasquale Panuzzo, CNRS researcher at the Paris-PSL Observatorymain author of the work published in Astronomy & Astrophysics Letters. Scientists from the Gaia consortium were in fact clearing the latest data from the probe, with a view to publishing the next catalog in 2025, when they came across a particular binary star system.
Already such behemoths, but “never in our galaxy”
“We saw a star a little smaller than the Sun (approximately 75% of its mass) and brighter, which revolved around an invisible companion”, identifiable by the disturbances it causes it to undergo, says Pasquale Panuzzo, responsible for deputy of Gaia’s spectroscopic processing.
Gaia gives the very precise position of the stars in the sky, so astronomers were able to characterize the orbits and measure the mass of the star’s invisible companion. Further observations from ground-based telescopes confirmed that it was indeed a black hole, with a mass much greater than that of the black holes of stellar origin already known in the Milky Way – between 10 and 20 solar masses.
Such behemoths have already been detected in distant galaxies, via gravitational waves. But “never in ours,” assures Dr. Panuzzo. And you should know that Gaia BH3 is a “dormant” black hole: it is too far from its companion star to remove its material and therefore does not emit any X-ray radiation, which makes its detection extremely difficult. The ESA (European Space Agency) Gaia probe, which has been operating 1.5 million kilometers from Earth for ten years, delivered in 2022 a 3D map of the positions and movements of more than 1.8 billion of stars.