'Hungriest ever' black hole discovered thanks to James Webb Space Telescope

Scientists have discovered a low-mass supermassive black hole feasting on material at a rate never seen before. A supermassive black hole is the largest type of black hole, with its mass being hundreds of thousands, or millions to billions, of times the mass of our Sun.

LID-568 is an "exciting" discovery because it appears to feed on matter at a rate 40 times its Eddington limit. This limit relates to the maximum luminosity that a black hole can achieve, as well as how fast it can absorb matter and remain in balance.

“This black hole is having a feast,” says International Gemini Observatory/NSF NOIRLab astronomer and co-author Julia Scharwächter. “This extreme case shows that a fast-feeding mechanism above the Eddington limit is one of the possible explanations for why we see these very heavy black holes so early in the Universe.”

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The discovery of LID-568 also shows that it’s possible for a black hole to exceed its Eddington limit, and provides the first opportunity for astronomers to study how this happens. The powerful outflows observed in LID-568 may be acting as a release valve for the excess energy generated by the extreme accretion, preventing the system from becoming too unstable.

Supermassive black holes exist at the centre of most galaxies, and modern telescopes continue to observe them at surprisingly early times in the Universe’s evolution. It’s difficult to understand how these black holes were able to grow so big and so rapidly.

LID-568 was discovered by a cross-institutional team of astronomers led by International Gemini Observatory/NSF NOIRLab astronomer Hyewon Suh. They used the James Webb Space Telescope (JWST) to observe a sample of galaxies from the Chandra X-ray Observatory’s COSMOS legacy survey. This population of galaxies is very bright in the X-ray part of the spectrum, but are invisible in the optical and near-infrared. JWST’s unique infrared sensitivity allows it to detect these faint counterpart emissions.

These results provide new insights into the formation of supermassive black holes from smaller black hole ‘seeds’, which current theories suggest arise either from the death of the Universe’s first stars (light seeds) or the direct collapse of gas clouds (heavy seeds).

Until now, these theories lacked observational confirmation. “The discovery of a super-Eddington accreting black hole suggests that a significant portion of mass growth can occur during a single episode of rapid feeding, regardless of whether the black hole originated from a light or heavy seed,” says Suh.