We just found 200 black holes that are way too fat—they weigh 100 times more than they should compared to the galaxies they live in.
March 25, 2026
Original Paper
A large population of over-massive black hole quasars at z=0.3-0.8 revealed by eROSITA
arXiv · 2603.22425
The Takeaway
Generally, a galaxy's central black hole is only 0.1% of its total mass, but these 'monsters' make up 5% to 10%. This discovery proves that giant black holes don't just happen in the early universe; they can grow independently of their stars even in more modern times.
From the abstract
In most galaxies, the central black hole accounts for no more than a percent of the total mass in stars. Recently, however, extremely over-massive black holes with ratios of 10% have been reported in dwarf galaxies at z 5.5) by JWST. Both findings have been interpreted as signatures of the still mysterious origins of super-massive black holes, such that most of the black hole mass was built at birth rather than through black hole accretion. Here we show that among evolved galaxies over-massive b