The James Webb Space Telescope has just captured the first direct measurement of a black hole 50 million times the mass of the Sun, sitting in an ancient galaxy where it outweighs every star around it — suggesting it may have formed first

According to the official ESA Webb announcement on 27 May 2026, two papers published the same day, one in Nature and a companion in Monthly Notices of the Royal Astronomical Society, report the first direct mass measurement of a supermassive black hole in the first billion years after the Big Bang. The object sits at the heart of a small, very red galaxy called Abell2744-QSO1, seen as it was roughly 700 million years after the Big Bang. The mass comes out at 50 million times the mass of the Sun. The galaxy around it is so faint that the central object accounts for around two-thirds of the total mass of the system and is more massive than all the stars in the galaxy combined. If the measurements hold, the implications run against the standard textbook account of how supermassive black holes form, which has the galaxy assembling first and the central black hole growing in step with it.

QSO1 belongs to a class of objects called Little Red Dots, first identified by the James Webb Space Telescope shortly after its commissioning in 2022. These are very compact, very red sources, common in the first billion years of cosmic history and almost entirely absent in the local universe. The Nature paper is co-first-authored by Ignas Juodžbalis, a Cambridge graduate student, and Cosimo Marconcini of the University of Florence, with Roberto Maiolino (Cambridge), Francesco D’Eugenio (Cambridge), Hannah Übler (Max Planck Institute for Extraterrestrial Physics), and Lukas Furtak (Ben-Gurion University) among the collaborators. The MNRAS companion paper is led by Maiolino.

How the measurement was made

Previous mass estimates for black holes in the first billion years had relied on indirect methods, mostly calibrated against scaling relations observed in the local universe. These methods give an answer but carry the assumption that the physics of black hole accretion in the distant past was broadly similar to what is observed nearby. According to Space.com’s report on the work, D’Eugenio explained the team’s concern with that approach plainly: “We didn’t know if those assumptions really apply to the distant universe.”

The way around the problem was to map the motion of the gas surrounding the black hole directly. Juodžbalis and Marconcini used the integral field unit on the JWST’s NIRSpec (Near Infrared Spectrograph) instrument to measure the velocity of gas at different radii from the centre of QSO1, looking for the signature pattern called Keplerian motion, in which gas at any given distance moves at a speed determined by the gravitational pull of the mass interior to it. This is the same principle by which the orbital speed of planets allows astronomers to weigh the Sun. If most of the mass at the centre of QSO1 were spread out among stars, the gas motion would be smoother and slower than pure Keplerian rotation. If the mass were concentrated in a single point-like object, the gas would follow the Keplerian curve precisely.

The gas turned out to be on Keplerian orbits. “This is important because it tells us that most of the mass of QSO1 is concentrated in the black hole at the center,” Juodžbalis said in the official press materials. “If the mass were more distributed, as it would be if there were a lot of stars, the gas would not have this perfect Keplerian rotation.” From the measured velocities, the team derived a black hole mass of approximately 50 million solar masses. “This is a phenomenal result,” said Marconcini. “It is the first direct measurement of a black hole mass within the first billion years after the Big Bang.” The full technical analysis is in the Nature paper.

What this means

The galaxy itself contains relatively few stars. According to Universe Today’s coverage of the papers, the stellar mass is constrained to be below roughly 20 million solar masses, and some analyses push the upper limit considerably lower. The black hole is therefore more massive than all the stars in its galaxy combined, by at least a factor of two and possibly far more. Set against the ratio observed in the local universe, where supermassive black holes account for roughly 0.1% of their host galaxies’ stellar mass, QSO1 is orders of magnitude over-massive. The authors note in the Nature paper that QSO1 sits about a factor of ten above even the most extreme cases of black-hole-heavy galaxies previously identified by the JWST. The gas surrounding the black hole is almost entirely hydrogen and helium, with metallicity below 1% of solar values — chemically nearly primordial.

The standard picture of supermassive black hole formation has the black hole growing alongside its host galaxy, in a feedback relationship that takes billions of years. QSO1 cannot have formed this way. The galaxy is too small to have fed the black hole through ordinary accretion, and the time elapsed since the Big Bang at the moment of observation is too short for slow co-evolution to have produced this result.

The team’s preferred interpretation, presented as such rather than as a conclusion, is that the black hole formed first and the galaxy is now assembling around it. Two routes have been discussed in the recent literature. The first is the heavy seed hypothesis, in which a massive primordial gas cloud collapses directly to form a black hole of perhaps 10,000 to 100,000 solar masses, skipping the stellar stage entirely. The second, more speculative, is the primordial black hole hypothesis, in which the black hole formed in the first fraction of a second after the Big Bang from density fluctuations in the very early universe. “It seems that we have found a black hole that does not have a substantial host galaxy and that has predated stellar processes,” Juodžbalis said in the press materials. “This is very exciting because it is evidence for primordial black holes or direct collapse black holes, which have been theorized but not confirmed.”

Maiolino called the result “a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.” That framing should be taken with the usual caveats that come with press-release language. What the papers establish, in a narrower and more defensible sense, is that the standard local scaling between black hole mass and host galaxy mass does not apply in the first billion years. Whether QSO1 is unusual among Little Red Dots, or whether the population as a whole follows the same pattern, is the next question the Cambridge–Florence team is pursuing.