A team of astronomers have used a bent light to locate one of the biggest black holes ever found. It’s hundreds of millions of light years from Earth and over 30 billion times the mass of the Sun.
The amazing discovery—described by the lead scientist as “extremely exciting”—was published this week in the journal Monthly Notices of the Royal Astronomical Society.
It was found using a technique called gravitational lensing —also known as an “Einstein ring”—which is when the gravitational field of a foreground object is so intense that it distorts the space around it and bends the light from an object behind it into circular rings, both revealing its existence and magnifying it.
Gravitational lensing is the best way to infer the presence of incredibly distant objects and measure their mass, though the team—led by Durham University in the UK—also used supercomputer simulations.
When an ultramassive black hole was used in the simulations the results matched the path seen in real images of deep space captured by the Hubble Space Telescope.
“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,” said lead author Dr James Nightingale, Department of Physics, Durham University. “Gravitational lensing makes it possible to study inactive black holes, something not currently possible in distant galaxies.”
It’s hoped that this new approach could allow astronomers to find more inactive and ultramassive black holes in the distant universe.
Our understanding of gravitational lensing and the incredible magnifying effect is has on the distant universe is a direct result of a prediction by Albert Einstein in his General Theory of Relativity. Einstein theorized that a gravitational field affects the path of a ray of light. Two British expeditions to observe a total solar eclipse on May 29, 1919 were able to take images of the stars of Gemini around the Sun. They proved to be slightly out of position compared to images of the same patch of sky taken at night, which indicated that the Sun slightly bends spacetime, causing light to travel in something other than a straight line. The result was announced on November 6, 1919.
The deflection of light by gravitational fields—or gravitational light bending—is now called gravitational lensing and has become a critical tool for cosmologists.