Astronomers find the nearest massive black hole to Earth

 Scientists have discovered a vast black hole more than 8,200 times the mass of our sun in a nearby star cluster which could unravel cosmic secrets.

Located at the heart of the Omega Centauri cluster 18,000 light years away, the super-dense object is the closest example of a massive black hole ever discovered, and the first confirmed 'intermediate' black hole.

Experts at Liverpool John Moores University were involved in locating the black hole, which was detected by analysing starts which were anomalously fast-moving.

Omega Centauri is a spectacular collection of about ten million stars, visible in the night sky from Southern latitudes, and we now know it contains a central black hole, of a type notoriously hard to find. There have been promising candidates, but no definite detection of such an intermediate-mass black hole – until now.

Led by Maximilian Häberle of the Max Planck Institute for Astronomy, the astronomers painstakingly measured velocities of stars in the search.

Dr Sebastian Kamann, of LJMU's Astrophysics Research Institute, sifted through spectroscopic data on stars, to prove unequivocally that their speeds were propulsed by the presence of a concentrated nearby mass.

Kamann worked with Häberle, who created an enormous catalogue for the motions of stars in Omega Centauri, measuring the velocities for 1.4 million stars by studying over 500 Hubble images of the cluster. Most of these images had been produced for the purpose of calibrating Hubble's instruments rather than for scientific use. But with their ever-repeating views of Omega Centauri, they turned out to be the ideal data set for the team's research efforts.

Häberle said looking for high-speed stars and documenting their motion was the proverbial search for a needle in a haystack k but they identified seven tell-tale, fast-moving stars in a small region in the centre of Omega Centauri.

The team now plan to examine the centre of Omega Centauri in even greater detail and have approval to use the James Webb Space Telescope.

Added Kamann: "One crucial piece of information we are currently lacking are line-of-sight velocities for the high-speed stars, which would enable us to study their motion in 3D and to pinpoint the black-hole mass even further.

"While the currently available data are too shallow for such measurements, we are confident that this will change once our James Webb observations have been taken."

https://www.ljmu.ac.uk/about-us/news/articles/2024/7/15/alphacentauri