Some black holes grow much faster than their galaxies

An artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. The study found eight quasars with black holes that are 20 to 1 in mass ratio, meaning the black holes make up about 5% of their galaxies’ mass. These black holes are consuming matter at an exceptional pace and could double in mass in a billion years. The galaxies hosting these black holes are particularly faint, suggesting they may not form as many stars as the Milky Way. The findings challenge the idea that black hole growth always follows galaxy growth. The study used the eROSITA X-ray telescope and observations of over 20,000 quasars to identify these unusual black holes. The results suggest a complex interaction between galaxies and their black holes, and more observations are needed to understand the mechanism. The study was published in Astronomy & Astrophysics in 2026.

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