Universe Today
Somewhere in the future, there's a finish line in the marathon to understand supermassive black holes (SMBH). We can't say how close we are, or what the final results will be. But astrophysicists keep going, confident that with each passing landmark, the finish draws nearer.
The effort to understand them became more earnest when the JWST was launched. Astrophysicists were suprised to find many SMBH in the early Universe. According to the understanding at the time, there shouldn't have been enough time for them to become so massive so soon.
New research is adding to the difficulty in understanding SMBH, turning it from a race into an obstacle course. Working with the JWST, researchers have found a SMBH with 50 million solar masses that appears to predate its host galaxy. This discovery is a direct challenge to what we thought we know about SMBH.
Astrophysicists understood, or thought they understood, that SMBH growth goes something like this: a massive star in a galaxy collapses into a black hole at the end of its life. This stellar-mass black hole grows by accreting surrounding material, and by merging with other stellar mass black holes doing the same thing. Galaxies also merge, driving their black holes to merge with them. Eventually, the process creates large galaxies with SMBH that can have billions of solar masses. It was still somewhat mysterious how small stellar mass black holes could be the seeds for much more massive SMBH, but the basic process was outlined.
Or so it was thought.
But now that the JWST has found an SMBH that appears to predate its galaxy, new questions demand answers.
“This is a remarkable finding. It’s a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.” - Roberto Maiolino, Kavli Institute.
Two new papers present the discovery. One is "A direct black-hole mass measurement in a little red dot at high redshift," published in Nature. The lead author is Ignas Juodžbalis from the Kavli Institute for Cosmology, at the University of Cambridge in the UK.
The other is "A black hole in a near pristine galaxy 700 Myr after the big bang," and it's published in the Monthly Notices of the Royal Astronomical Society. The lead author is Roberto Maiolino, also from the Kavli Institute at Cambridge. The lead authors of both papers are also co-authors on the other paper.
“This is a remarkable finding,” Maiolino said in a press release. “It’s a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.”
The finding arises from the observations of Abell2744-QSO1, a protoypical Little Red Dot (LRD) from only 700 million years after the Big Bang. Despite its small size, only 1,300 light years across, the LRD is accessible to detailed observations. That's because it's gravitationally lensed by galaxy cluster Abell 2744, also known as Pandora's Cluster. The lensing both magnifies QS01 and triples it.
Prior to this work, initial observations showed that QS01 was no more than a cloud of gas with a 40 million solar mass SMBH. It's mass measurement wasn't certain because astronomers weren't accustomed to finding such massive SMBHs so early in the Universe.
"Before now, all of the mass measurements of black holes in the early Universe have been indirect, based on assumptions from what we know about them in the local Universe. We didn’t know if those assumptions really apply to the distant Universe," said co-author Francesco D’Eugenio, also of Cambridge University.
If the SMBH was that massive, then it should be affecting the surrounding gas in a measurable way. Researchers used the integrated field unit on the JWST's NIRSpec to determine the SMBH's gravitational effect on the surrounding gas, and to map the various elements present in it. By determining the rotational velocity of the gas, it confirmed that the gas is orbiting a central object.
*This detail from Webb’s NIRCam shows the Little Red Dot Abell2744-QSO1, gravitationally lensed by Abell 2744, an enormous mega-cluster of galaxies also known as Pandora’s Cluster. The panel on the right shows the gas velocity, or rotational velocity, of QS01. Webb's observations show that the gas in the LRD has Keplerian motion, meaning its orbiting a central point, just like Kepler figured out for planets orbiting stars. Since Kepler's laws are so well understood, this let the researchers measure the LRD's mass. The SMBH contains about 50 millions solar masses, which is a shocking two-thirds of the entire mass of the SMBH/LRD system. Image Credit: NASA, ESA, CSA, L. Furtak (Ben-Gurion University), R. Maiolino (Cambridge), F. D'Eugenio (Cambridge), I. Juodžbalis (Cambridge), H. Übler (MPE), C. Marconcini (University of Florence). Image processing: A. Pagan*
“This is important because it tells us that most of the mass of QSO1 is concentrated in the black hole at the centre,” said Juodžbalis. “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."
Keplerian motion is well understood, and that let the astronomers measure the mass of the central SMBH with greater accuracy. Those measurements revealed that the SMBH was 50 million solar masses, 10 million more than thought. The measurements also revealed something else: the SMBH makes up a massive portion of the galaxy's mass, something we don't see in galaxies in the local Universe.
"QSO1 lies orders of magnitude above the local scaling relations and is approximately 1 dex more overmassive than even the most extreme sources found by JWST so far," the authors write in the first paper.
This figure from the first paper compares the mass of the SMBH to that of its galaxy, the MBH/M⁎ ratios, for both QS01 and other low-mass AGN detected by the JWST. The solid green line is the local scaling relation, what we see in the local Universe. "QSO1 lies orders of magnitude above the local scaling relations," the authors write. Image Credit: Juodžbalis et al. 2026. Nature.
"These results represent a direct, dynamical measurement of a BH mass at z > 5 and in an LRD," the authors of the first paper write.
The NIRSpec IFU observations also revealed that the gas in the galaxy is almost entirely hydrogen and helium, with very few astronomical metals. If the galaxy had lots of stars, NIRSPec should've revealed the presence of astronomical metals like oxygen, created when massive stars live and die.
"It is challenging for most models to account for such a chemically unevolved system that host a BH that is already so massive," the authors explain in the second paper.
“This is a phenomenal result,” said Maiolino. “It is the first direct measurement of a black hole mass within the first billion years after the Big Bang, and it is consistent with the previous measurements.” Even though the new measurements show it has 50 million solar masses rather than 40 million, that doesn't materially change the JWST's findings of massive SMBH so early in the Universe.
But it does provide proof that black holes don't grow in the orderly, heirarchical way that astrophysicists thought they did. "The only scenarios that can account for such a system are those invoking ‘heavy seeds’, such as direct-collapse BHs (resulting from the direct collapse of massive pristine clouds) or primordial BHs (formed in the first second after the Big Bang)," the authors write in the first paper.
"It seems that we have found a black hole that does not have a substantial host galaxy and that has predated stellar processes,” said Juodžbalis. “This is very exciting because it is evidence for primordial black holes or direct collapse black holes, which have been theorised but not confirmed."
Primordial black holes (PBH) are theorized to have formed in the early Universe when the physics were much different. They had no stellar precursors and collapsed directly from gas. "PBH scenarios seem to better reproduce the properties of QSO1, but even these scenarios require further developments to self-consistently explore the BH and metallicity evolution," the authors of the second paper write.
This artist's illustration shows what primordial black holes could look like. They could have formed in the very early Universe, when physics were much different. Some theorists say they could be the precursors to SMBH in the early Universe. Image Credit: NASA.
Somehow, QSO1 was born large, whether it formed from a theorized heavy seed immediately after the Big Bang, or sometime later through direct collapse in a gas cloud, much like stars form. It could be in the early stages of forming a galaxy around itself. In any case, the JWST has discovered hundreds of the Little Red Dots (LRD), so whatever they are, they're not rare and are not outliers.
"It is too early to quantitatively assess the fraction and density of extremely metal-poor AGN, and in particular LRDs, in the early Universe, and certainly more observations and statistics are needed," the authors of the second paper write. "However, we note that QSO1-like BHs cannot be so uncommon."
Deeper analysis of LRDs, hopefully with the aid of more gravitational lenses, will help astrophysicists clear this hurdle for good. Once they have determined exactly what QS01 and LRDs are, the finish line in the marathon to understand SMBH will be closer.
But, of course, we haven't seen everything. There are bound to be more unexpected hurdles, brought into view by the next most powerful telescope.
