‘Ultramassive Black Hole’ of 33 Billion Solar Masses Discovered

Astronomers from Durham University, in collaboration with the Max Planck Institute for Astrophysics, have discovered one of the biggest black holes ever found — over 30 billion times the mass of the Sun — by taking advantage of a phenomenon called gravitational lensing. This is the first black hole ever known to be found using this technique, as detailed in the Monthly Notices of the Royal Astronomical Society.

A gravitational lens occurs when the gravitational field of a foreground galaxy appears to bend the light of a background galaxy, meaning that we observe it more than once. Like a real lens, this also magnifies the background galaxy, allowing scientists to study it in enhanced detail.

“Most of the biggest black holes that we know about are in an active state, where matter pulled in close to the black hole heats up and releases energy in the form of light, X-rays and other radiation,” said Durham’s Dr James Nightingale, lead author of the study.

“However, gravitational lensing makes it possible to study inactive black holes, something not currently possible in distant galaxies. This approach could let us detect many more black holes beyond our local universe and reveal how these exotic objects evolved further back in cosmic time.”

The use of gravitational lensing and supercomputer simulations from the UK’s DiRAC high-performance computing facility enabled the team to closely examine how light is bent by a black hole inside a galaxy hundreds of millions of light years from Earth. They simulated light travelling through the universe hundreds of thousands of times, with each simulation including a different mass black hole, changing light’s journey to Earth.

When the researchers included an ultramassive black hole in one of their simulations, the path taken by the light from the faraway galaxy to reach Earth matched the path seen in real images captured by the Hubble Space Telescope. The team had indeed discovered an ultramassive black hole, over 30 billion times the mass of our Sun, in the foreground galaxy — a scale rarely seen by astronomers.

“This particular black hole … is one of the biggest ever detected and on the upper limit of how large we believe black holes can theoretically become, so it is an extremely exciting discovery,” Nightingale said.

The study opens up the possibility that astronomers can discover far more inactive and ultramassive black holes than previously thought, and investigate how they grew so large. Indeed, the researchers hope this is the first step in enabling deeper exploration of the mysteries of black holes, and that future large-scale telescopes will help astronomers study even more distant black holes to learn more about their size and scale.