Black holes ranging from roughly ten solar masses to millions of times the Sun's mass appear to launch jets according to the same underlying rule, according to a study published in Nature Astronomy. Led by Dr. Adelle Goodwin of Curtin University and co-author Dr. Andrew Mummery of the Institute for Advanced Study in Princeton, the work connects jet behaviour in small black holes to dramatic eruptions in their supermassive counterparts.
The researchers focused on tidal disruption events, in which a supermassive black hole tears apart a passing star. Using observations in visible light, ultraviolet, X-rays, and radio from telescopes around the world, they examined how these black holes behave as their feeding rate changes. Some events produced jets almost immediately, while others stayed quiet for months or years before a radio outflow appeared.
The delayed jets turned out to switch on at a consistent point: when the black hole's feeding rate fell to roughly 2% of its Eddington limit, a standard measure of the balance between radiation pressure and gravity. That same threshold was already known to govern jet formation in much smaller black holes, and the team says it appears to apply across size scales.
Astronomers have long suspected that black holes obey shared physical laws regardless of mass, but testing that idea is difficult because supermassive black hole feeding cycles can last thousands of years. Tidal disruption events compress that cycle into a few years, making direct comparison possible. The findings could help predict when black holes will erupt after consuming a star, and how those outflows affect their host galaxies. Because this summary is based on a single source, no conflicting findings are noted.