The Black Holes That Grew Too Fast
A Speed Limit Problem
Black holes grow by eating, and eating has a speed limit. As gas spirals into a black hole, it heats up and radiates light, and that radiation pushes back against the gas trying to fall in behind it. The point where outward radiation pressure balances inward gravity is called the Eddington limit, and it caps how fast any black hole can put on mass through ordinary accretion. Euclid, the European Space Agency telescope operating 1.5 million kilometers from Earth with NASA as a contributing partner, used spectroscopy to confirm 31 new quasars from the universe's first 800 million years, published July 6, 2026 in a dedicated issue of Astronomy & Astrophysics. Two of them, cataloged as EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, date to roughly 670 million years after the Big Bang, about 20 million years older than the previous record holder. Lead author Daming Yang, a Leiden University PhD student, and co-author Joseph Hennawi confirmed each is powered by a black hole already around a billion solar masses. Run the Eddington math backward from a billion solar masses to a plausible starting seed, a black hole formed from one collapsed star, and there is not enough time in 670 million years to get there. Not close.
Confirmed Versus Contested
This is where the evidence test matters, because the field currently has two competing objects and only one of them is confirmed. Euclid's quasars are spectroscopically verified: astronomers split the light and read the chemical and velocity signatures that only a black hole accretion disk can produce. JWST found a parallel population, the so-called 'little red dots', compact, deeply red objects from a similar era, and there's a live disagreement over whether they are black holes at all or extremely dense clusters of old, dust reddened stars. Imperial College London's Daniel Mortlock, who co-leads Euclid's Quasar Work Package, described isolating these 31 objects across the telescope's enormous survey area as 'the ultimate needle in a haystack problem', and the number backs him: in its first year of science operations Euclid confirmed 12 billion solar mass quasars, matching roughly what every other telescope combined had found in the prior decade. That haul is the real product of the mission's $1.5 billion, six year budget: not a record, but a confirmed comparison sample. Researchers trying to interpret the ambiguous JWST objects finally have something certain to calibrate against, and 'heavy seed' formation, a massive gas cloud collapsing directly into a black hole with no star-forming detour, is the model gaining ground because it needs less time.
Heavy seed formation solves the timing problem on paper, but nobody has directly observed a gas cloud collapsing straight into a black hole without ever igniting as a star. Confirming it requires catching a heavy-seed candidate in the act, a direct image of a collapsing gas cloud before any star ignites, which no telescope has yet delivered. Euclid's confirmed sample now gives astronomers a control group for the harder puzzle next door: whether the disputed JWST little red dots turn out to be scaled down versions of these same quasars, a question follow-up JWST spectroscopy on individual little red dots is now positioned to resolve.
Sources
- NASA Science (science.nasa.gov)
- CBS News (cbsnews.com)
- Imperial College London (imperial.ac.uk)
- Astronomy & Astrophysics (aanda.org)
- University of Arizona (news.arizona.edu)