The newly-discovered ultramassive black hole has a mass of 32.7 billion solar masses and resides in the center of Abell 1201 BCG, a massive elliptical galaxy in the galaxy cluster Abell 1201.
This image shows the strong-lensing galaxy Abell 1201 BCG and a gravitational arc. Image credit: NASA / ESA / Hubble / Nightingale et al., doi: 10.1093/mnras/stad587.
Supermassive black holes are a key catalyst of galaxy formation and evolution.
Outside the local Universe, measurements of the mass of a supermassive black hole are usually only possible for supermassive black holes in an active state: limiting sample size and introducing selection biases.
Gravitational lensing — where a foreground galaxy bends the light from a more distant object and magnifies it — makes it possible to measure the mass of supermassive black holes.
“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 University astronomer James Nightingale.
“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.”
In the new study, Dr. Nightingale and colleagues used gravitational lensing and supercomputer simulations on the DiRAC HPC facility, which enabled them to closely examine how light is bent by a supermassive black hole inside Abell 1201 BCG.
This is the first black hole found using the technique, whereby the astronomers simulate light traveling through the Universe hundreds of thousands of times.
Each simulation includes 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 NASA/ESA Hubble Space Telescope.
“This particular black hole, which is roughly 30 billion times the mass of our Sun, 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,” Dr. Nightingale said.
The discovery is described in a paper in the Monthly Notices of the Royal Astronomical Society.
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J.W. Nightingale et al. 2023. Abell 1201: detection of an ultramassive black hole in a strong gravitational lens. MNRAS 521 (3): 3298-3322; doi: 10.1093/mnras/stad587
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Natali Anderson