Astronomers discover the fastest-feeding black hole in the early Universe

• Observations from JWST telescope and the Chandra X-ray Observatory reveal a low-mass black hole that appears to be consuming matter at over 40 times the theoretical limit
• This black hole’s ‘feast’ could help scientists explain how supermassive black holes grew so quickly in the early Universe
• Mar Mezcua, IEEC researcher at the Institute of Space Sciences (ICE-CSIC), participated in the study published in Nature Astronomy

A team led by the U.S. National Science Foundation NOIRLab has discovered a low-mass black hole at the centre of a galaxy just 1.5 billion years after the Big Bang that is consuming matter at a phenomenal rate: over 40 times the theoretical limit. The study has the participation of Mar Mezcua, researcher from the Institute of Space Studies of Catalonia (IEEC — Institut d’Estudis Espacials de Catalunya) at the Institute of Space Sciences (ICE-CSIC), and has been published today in Nature Astronomy. 

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 so rapidly. But with the discovery of a low-mass black hole feasting on material at an extreme rate, seen just 1.5 billion years after the Big Bang, astronomers now have valuable new insights into the mechanisms of rapidly growing black holes in the early Universe.

The black hole LID-568 was discovered by a cross-institutional team of astronomers led by the International Gemini Observatory/NSF NOIRLab. 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 is invisible in the optical and near-infrared. The JWST telescope’s unique infrared sensitivity allows it to detect these faint counterpart emissions.

“Most of the early Universe black holes detected by the JWST are very faint (or undetected) in X-rays, but LID-568 caught our attention because of its high X-ray brightness”, says Mar Mezcua, IEEC researcher at the ICE-CSIC and co-author of the study. 

LID-568 stood out within the sample for its intense X-ray emission, but its exact position could not be determined from the X-ray observations alone, raising concerns about properly centering the target in JWST’s field of view. So, rather than using traditional slit spectroscopy, JWST’s instrumentation support scientists suggested that the team use the integral field spectrograph on JWST’s NIRSpec instrument. This instrument can get a spectrum for each pixel in the instrument’s field of view rather than being limited to a narrow slice.

JWST’s NIRSpec allowed the team to get a full view of their target and its surrounding region, leading to the unexpected discovery of powerful outflows of gas around the central black hole. The speed and size of these outflows led the team to infer that a substantial fraction of the mass growth of LID-568 may have occurred in a single episode of rapid accretion. “This serendipitous result added a new dimension to our understanding of the system and opened up exciting avenues for investigation,” says Gemini Observatory/NSF NOIRLab astronomer Hyewon Suh, leader of the study. 

The team found that LID-568 appears to be feeding 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, such that its inward gravitational force and outward pressure generated from the heat of the compressed, infalling matter remain in balance. When LID-568’s luminosity was calculated to be so much higher than theoretically possible, the team knew they had something remarkable in their data.

“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.”

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 Hyewon Suh.

The discovery of LID-568 also shows that it’s possible for a black hole to exceed its Eddington limit, and provides a great opportunity for astronomers to study how this happens. It’s possible that 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. To further investigate the mechanisms at play, the team is planning follow-up observations with JWST.

Press release prepared in collaboration with the Institute of Space Sciences.

More information

This research is presented in a paper entitled “A super-Eddington-accreting black hole ~1.5 Gyr after the Big Bang observed with JWST”, by Hyewon Suh, Julia Scharwächter et al., to appear in the journal Nature Astronomy on 4 November 2024. DOI: 10.1038/s41550-024-02402-9.

Links

• IEEC
• ICE-CSIC
• JWST
• NSF NOIRLab

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About the IEEC

The Institute of Space Studies of Catalonia (IEEC — Institut d’Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of more than 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centres, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC’s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.

The IEEC is a non-profit public sector foundation that was established in February 1996. It has a Board of Trustees composed of the Generalitat de Catalunya, Universitat de Barcelona (UB), Universitat Autònoma de Barcelona (UAB), Universitat Politècnica de Catalunya · BarcelonaTech (UPC), and the Spanish Research Council (CSIC). The IEEC is also a CERCA centre.