James Webb Finds Evidence of Three Feeding Black Holes in Ancient Galaxy

The James Webb Space Telescope has found evidence of three massive black holes actively feeding inside a single galaxy seen as it existed when the Universe was about 1.2 billion years old. The international team led by the Max Planck Institute for Extraterrestrial Physics identified two apparent black holes near the galaxy’s center and a third in its outskirts.

The result is not a direct image of three black holes. It is a spatially resolved measurement of fast-moving hydrogen gas, with three distinct emission regions that researchers concluded are best explained by matter falling toward three black holes. That distinction matters: Webb has supplied unusually detailed observational evidence, while the system’s merger history and future remain scientific interpretations.

How Webb separated three hidden objects

The galaxy, designated J0148-4214, has a reported redshift of about 5.02. Its light traveled for more than 12.5 billion years before reaching Webb, giving astronomers a view of the galaxy during an early period of cosmic development.

Researchers used Webb’s Near-Infrared Spectrograph, or NIRSpec, in integral-field spectroscopy mode. Conventional spectroscopy separates light by wavelength, revealing the chemical and physical signatures within an object. Integral-field spectroscopy adds spatial information, allowing scientists to compare spectra from different locations across a galaxy rather than blending the entire target into one measurement.

The important signature was broad hydrogen emission, particularly the H-alpha line. A broadened line indicates that the emitting gas spans a large range of velocities. Gas moving rapidly within the strong gravitational environment around an actively accreting black hole can produce that pattern.

Near the center of J0148-4214, the emission had a complex structure best explained by two nearby sources. The team used spectro-astrometry, which measures small shifts in the position of line emission, to distinguish them even though Webb could not resolve the two black holes as separate point sources. A third broad-line region appeared farther out in the galaxy.

This spatial separation is the mission’s central technical contribution. Without NIRSpec’s location-by-location spectral information, the combined light would probably have revealed only one active black hole rather than three.

What the measurements establish

The two central candidates are separated in projection by roughly 620 light-years. Their estimated masses are markedly different: about 80 million times the Sun’s mass for the larger object and approximately 600,000 solar masses for its smaller neighbor. The third candidate has an estimated mass of around two million Suns and lies roughly 5,500 light-years from the main black hole in projection.

“In projection” is an important boundary on those figures. The observations measure apparent separation across the sky, not the objects’ complete three-dimensional positions. Their actual distances from one another could therefore be greater.

The researchers considered other possible sources of broad emission, including stellar explosions, shocks and winds. Their analysis favored active black holes, meaning black holes surrounded by accreting material, as the explanation for all three regions. The study, described as BlackTHUNDER, was published in Astronomy & Astrophysics.

A merger pathway, not an observed merger

The close central pairing supports the idea that galaxy interactions can bring massive black holes together early in cosmic history. Such pairings could provide a faster growth route than feeding on surrounding gas alone: when black holes eventually merge, their combined object is more massive.

But Webb did not observe a merger. The team estimated that the central pair could lose orbital energy and combine in less than roughly 700 million years. That timescale is a modeled outcome based on the interpreted system, not a confirmed future event captured in the data.

The outer object introduces another unresolved part of the investigation. Its position may reflect an earlier interaction involving smaller galaxies, or it may be moving inward. Those scenarios could help reconstruct how J0148-4214 assembled, but its location by itself does not confirm either history.

The stronger result is narrower and more consequential for Webb: spatially resolved spectroscopy separated three apparent accretion signatures that would otherwise have overlapped. Future observations will have to test the proposed interaction history, but NIRSpec has already shown that some apparently single active galaxies in the early Universe may conceal multiple growing black holes.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.