Three feeding black holes in one galaxy: a first glimpse of how cosmic monsters assemble

Astronomers have found three actively feeding supermassive black holes inside a single galaxy in the distant universe — the first time such a trio has ever been identified in one system. The galaxy, J0148-4214, is seen as it was just 1.2 billion years after the Big Bang, and the discovery offers a direct look at how the early universe may have driven massive black holes together, setting up the mergers that future gravitational-wave observatories hope to detect. The work, led by Hannah Übler at the Max Planck Institute for Extraterrestrial Physics, was published in Astronomy & Astrophysics.

Three engines, one galaxy

J0148-4214 lies more than 12.5 billion light-years away, at a redshift of z = 5.02. Two of its three black holes sit in the galactic center, separated by only about 620 light-years in projection; the third lies far out in the galaxy’s outskirts, roughly 5,500 light-years from the center. Each is surrounded by an accretion disk actively pulling in matter — all three are switched on and feeding.

The masses come out to roughly 80 million, 0.6 million, and 2 million solar masses. Notably, the most massive of the three is accreting more slowly than its smaller central companion, which is feeding so vigorously that it exceeds the Eddington limit — the maximum accretion rate that basic black-hole growth theory predicts. Against a total stellar mass of about 1.3 billion solar masses for the whole galaxy, the three black holes together make up a significant fraction, an unusually top-heavy balance that fits the broader picture of overmassive black holes in the early universe.

Pulling three sources out of one blur

Detecting three black holes in a galaxy this distant required a technique capable of separating sources that cannot be resolved as individual points of light. The team identified the black holes by their spectral fingerprints — hydrogen atoms whipping around at high velocity in each black hole’s gravitational well. In the center, the spectrum showed a complex structure best explained by two black holes in close proximity.

To disentangle them, the researchers applied spectro-astrometry, which precisely measures tiny spatial shifts in line emission across the galaxy, pinning down the positions of the two central sources even without resolving them separately. A third black hole then emerged in the outer region. The whole result rests on the spatially resolved data from JWST’s NIRSpec integral field spectrograph — without it, the team notes, only one of the three black holes would likely have been found at all.

A fast track to cosmic giants

The central pair is expected to merge within the next few hundred million years, and the finding suggests that black-hole merging may be an additional, rapid route to the enormous masses seen so early in cosmic history. The third, off-nucleus black hole is more of a puzzle: it may be the leftover from an earlier merger, an object kicked away from the center by a gravitational recoil, or one currently migrating inward.

Beyond this single system, the result demonstrates that integral field spectroscopy is now a key tool for uncovering multiple active black holes in distant galaxies — hinting that other early galaxies may host similar hidden multiples, waiting for the same technique to reveal them.

© 2026 Homer Dávila Gutiérrez, FRAS — SKYCR.ORG. All rights reserved. Publication: Hannah Übler et al., BlackTHUNDER: Evidence of three massive black holes in a z ∼ 5 galaxy, Astronomy & Astrophysics (2026). DOI: 10.1051/0004-6361/202557419