Astronomers have finally explained how 'impossible' black holes 100 times larger than their host galaxies existed at the dawn of time.
March 31, 2026
Original Paper
How Overmassive Black Holes Formed at Cosmic Dawn
arXiv · 2603.28682
The Takeaway
The James Webb Space Telescope recently found massive black holes in the early universe that shouldn't have had enough time to grow. This simulation shows they didn't grow slowly; they were born as giants from collapsing clouds of primordial gas, fundamentally changing our timeline of how the universe began.
From the abstract
Overmassive black hole galaxies (OBGs) at redshifts $z \sim$ 10, or 450 Myr after the Big Bang, are one of the most puzzling discoveries by the James Webb Space Telescope to date because they formed by such early epochs and their black-hole to stellar mass ratios are a hundred times higher than those in galaxies today. Here we show that OBGs are simply the result of DCBH birth in primordial halos at early times. A 70,000 M$_{\odot}$ DCBH forming at $z =$ 25.7 in our cosmological simulation grows