Study finds black holes of all sizes may launch jets at the same feeding threshold

By the Everything Space news desk · 17 Sep 2026 · written from the sources below

Image: Phys.org

Researchers found stellar-mass and supermassive black holes trigger radio jets when accretion drops to about 2% of a key limit, hinting at universal physics.

Astronomers have found evidence that black holes ranging from a few times the mass of the sun to millions of times heavier may launch their radio jets according to the same underlying rule, based on how fast they are feeding rather than their size.

The research, led by an astrophysicist at Curtin University's International Center for Radio Astronomy Research along with a colleague at the Institute for Advanced Study, grew out of a puzzle: some black holes produce jets soon after devouring material, while others do so only after a long delay. The team traced this back to a common trigger point in the feeding process.

To test the idea, the researchers studied tidal disruption events, in which a star is shredded after passing too close to a supermassive black hole. These events compress what would normally be a slow feeding process into a matter of years, making it possible to observe stages that would otherwise unfold over millennia.

By combining optical, ultraviolet, X-ray and radio data from telescopes in multiple countries, the team analyzed 20 tidal disruption events and modeled the feeding rate and jet timing for 10 of them. They identified two separate jet-producing phases: one during the earliest, most intense feeding, and another much later when the feeding rate falls to roughly 2 percent of the Eddington limit, the point where radiation pressure pushing outward balances the pull of gravity inward. That same threshold has previously been linked to jet formation in much smaller stellar-mass black holes.

The consistency of this threshold across such different black hole masses suggests that the physics governing jet formation does not depend strongly on scale.

Beyond the theoretical implications, the finding could help astronomers plan observations more efficiently. Knowing when a black hole is likely to switch on a jet would let researchers target radio telescopes, including the upcoming Square Kilometer Array Observatory, at the right moments rather than conducting broad, resource-intensive searches.

As surveys uncover more tidal disruption events in the future, having a physical marker for when jets are likely to appear could make follow-up observations far more effective, researchers say.

Written in Everything Space’s own words by our news-desk model from the sources above, and checked against them in code: every number in this report appears in its sources, and no sentence is copied from them.