For the first time, scientists have measured the instantaneous power of jets blasting from a black hole. An international research team reported the jets from Cygnus X-1—a binary system 7,200 light-years away in the Milky Way’s Cygnus constellation—release energy equivalent to 10,000 suns. The jets travel at roughly 355 million mph, half the speed of light, the researchers announced Thursday in Nature Astronomy.
The measurement reveals how black holes influence galactic evolution. About 10 percent of all energy released as matter falls toward the black hole is carried away by the jets, which inject enormous amounts of energy into the interstellar medium, creating shocks and turbulence that can suppress star formation across entire galaxies.
The Cygnus X-1 System
Cygnus X-1 is a binary system consisting of a black hole and a blue supergiant star, located 7,200 light-years away in the Milky Way’s Cygnus constellation. The black hole was the first ever identified, discovered in the 1960s. As the stars orbit one another, the black hole continuously pulls gases from its stellar companion.
How Scientists Measured the Unmeasurable
The research, led by Steve Prabu of the University of Oxford, was based on 18 years of high-resolution radio imaging obtained by a global telescope network. Prabu conducted the research while at Australia’s Curtin University, which led the study published in Nature Astronomy.
Scientists had previously been able only to average a black hole’s jet power over tens of thousands of years. Prabu’s team took a different approach, calculating jet power by measuring how much the jets were bent by the stellar wind, then using computer modeling to extract the instantaneous power.
The stellar wind acts as a probe. As the supergiant star feeds material to the black hole, it also generates a powerful wind that deflects the jets ejected from the black hole’s accretion disk. By measuring the bending angles, the researchers could infer the force being applied by the wind and, from that, the power of the jets.
The Findings
The jets from Cygnus X-1 travel at roughly 355 million mph—half the speed of light—and carry energy equivalent to 10,000 suns. A critical finding: 10 percent of all energy released as matter falls toward the black hole is carried away by the jets.
The remaining energy goes to other forms of radiation and heating. This 10 percent represents a substantial fraction of the black hole’s energy output, revealing the jets as one of the most efficient mechanisms by which black holes redistribute energy to their surroundings.
Implications for Cosmic Evolution
Black hole jets are essential to understanding how black holes influence galactic evolution. Jets inject enormous amounts of energy into the interstellar medium, creating shocks and turbulence that can suppress star formation over vast cosmic distances.
Prabu said his team plans to apply the same measurement technique to other black hole systems. “It would be exciting to measure jet power in many more systems,” he said in an email. By building a systematic understanding of how jet power relates to black hole mass and accretion rate, scientists hope to better understand how black holes help shape the large-scale structure of the universe.