Astronomers using the James Webb Space Telescope have identified three supermassive black holes inside a single ancient galaxy, observed as it existed roughly 1.2 billion years after the Big Bang. The discovery offers new insight into how massive celestial bodies merged and grew rapidly in the early universe.
Light traveling across space for more than 12.5 billion years has brought into view an ancient galaxy known as J0148-4214. Inside that distant system, an international team led by researchers at the Max Planck Institute for Extraterrestrial Physics detected three actively accreting supermassive black holes, drawing in matter from their surrounding disks.
The expansion of the universe stretches the galaxy’s light toward longer wavelengths, creating a redshift of z=5.02 that allowed astronomers to calculate its vast distance and early cosmic age. The findings were described in a study published in the journal Astronomy & Astrophysics on August 12.
Mapping the Galactic Center and Outskirts of J0148-4214
Pinpointing three active black holes within one galaxy required advanced spectroscopic tools. Researchers traced the objects through distinctive spectral signatures produced by hydrogen atoms swirling at extreme speeds under intense gravitational pull. Because the central pair stood too close to resolve directly as individual points of light, the team applied spectro-astrometry, which measures tiny spatial shifts in emission lines across a galaxy, to determine their positions.
This is the first evidence of three active black holes in a single galaxy in the distant Universe,
says Hannah Übler, research group leader at MPE and lead author of the study.
Two of the black holes sit near the galactic center, separated by a projected distance of just 620 light-years. A third black hole sits roughly 5,500 light-years away in the galaxy’s outer region. Mass estimates place the two central objects at roughly 80 million and 0.6 million times the mass of the Sun, while the outlying black hole weighs in at about two million solar masses. The system’s total stellar mass measures approximately 1.3 billion suns, and the black holes represent a significant fraction of that.
Accrates and Extreme Growth Rates in the Ancient Universe
The feeding habits of the central pair present a puzzle for standard models of black hole growth. The most massive black hole, at 80 million solar masses, feeds more slowly than its smaller 0.6-million-solar-mass companion. That smaller neighbor accretes matter so rapidly that it exceeds the maximum rate predicted by basic models of black hole growth, known as the Eddington limit.
The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates, and the stellar mass of the galaxy,
says Dr. Giovanni Mazzolari, second author of the study and researcher at MPE.
The discovery underscores how efficiently the ancient cosmos brought massive objects together. As researchers note, the two central black holes are expected to merge within the next few hundred million years.
It suggests that processes in the early Universe were efficient at bringing massive black holes together, setting the stage for the massive black hole mergers we expect to detect with future gravitational wave observatories,
says Übler.
Meanwhile, the loner black hole might also one day join the celestial collision, or it may have been flung there as part of an even earlier merger.
Implications for Future Gravitational-Wave Observatories
Understanding how supermassive black holes grew so large so quickly has long challenged astrophysicists. Scientists suspect that black holes typically slowly gain mass by consuming gas, but they can sometimes quickly balloon by merging with one another. To understand how the latter may have happened soon after the Big Bang some 13.8 billion years ago, the team pointed JWST toward J0148-4214.
So, how have we ended up in a situation where these three supermassive black holes have formed and come close together in only a billion years or so since the Big Bang?
says Dougal Dobie, an astrophysicist at the University of Sydney in Australia who wasn’t involved in the study.
The findings establish that multiple active black holes can form and interact within single galaxies soon after the beginning of the universe, pointing to new mechanisms driving growth during cosmic dawn.
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