NASA's Chandra X-ray Observatory and the James Webb Space Telescope have discovered the most distant black hole ever seen with X-rays.
The discovery, just 470 million years after the Big Bang, lends strong weight to the theory that supermassive black holes start their lives massive, rather than growing over time.
The black hole, located in the galaxy UHZ1, was initially detected in the infrared by the Webb Telescope, and later observations by Chandra detected strong X-ray emission.
„We needed Webb to find this remarkably distant galaxy and its supermassive black hole,” says Agos Bogdan of the Harvard and Smithsonian Center for Astrophysics, who led the study.
„We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected.”
Gravitational lensing
The magnification used to detect a black hole is an effect called gravitational lensing.
Light from UHZ1 is bent by the gravitational pull of a near-Earth galaxy.
This magnified the image as light passed through the lens, and allowed Chandra to detect the galaxy's X-ray emission.
It showed the presence of superheated gas – a sign that a supermassive black hole is at its core.
How is a black hole so big?
Such primordial black holes are a boon to those trying to answer one of cosmology's biggest questions: How did supermassive black holes grow so large?
The two leading theories are that they started as black holes 10 to 100 times smaller than our Sun, or that they were already born at 10,000 to 100,000 solar masses.
UHZ1's black hole appears to have between 10 and 100 million solar masses, around the same mass as all the stars in the host galaxy combined.
By comparison, nearby supermassive black holes have only 0.1% the mass of their host galaxies.
UHZ1 may be an example of an 'outsize black hole', an idea first proposed by Priyamvatha Natarajan of Yale University in 2017, whereby supermassive black holes form directly from the collapse of a massive gas cloud.
„We think this is the first detection of an 'outsize black hole' and the best evidence that some black holes form from massive gas clouds,” says Natarajan.
„For the first time we see a supermassive black hole carrying the weight of the stars in its galaxy and a brief phase before it falls back.”