Researchers led by Steve Prabu of the University of Oxford have measured the instantaneous power of black hole jets for the first time. According to a study published in Nature Astronomy, the jets from Cygnus X-1, a relatively nearby black hole system, release energy equivalent to 10,000 suns.
The jets travel at approximately 355 million miles per hour—roughly half the speed of light—measured using 18 years of radio-telescope observations from a global network of instruments. Cygnus X-1 lies 7,200 light-years away and contains both a black hole and a blue supergiant companion star.
Until now, researchers could only average black hole jet power over tens of thousands of years because the jets were too faint and distant to measure directly. This breakthrough may help scientists understand how black holes shape galaxies and cosmic structures through the jets they produce.
How stellar winds reveal jet power
Prabu’s team measured the jets by calculating how much they bent under pressure from winds flowing from the blue supergiant star. The stellar wind continuously pushes the jets in opposite directions, creating oscillations the researchers detected and analyzed through computer modeling. This approach enabled real-time power calculations rather than averaging over millennia.
The measurement required unprecedented precision and a global network of radio telescopes working in concert. Observations spanning nearly two decades provided the temporal baseline needed to track the jets’ behavior across multiple cycles of oscillation caused by stellar wind pressure.
The efficiency of black hole jets
The blue supergiant star continuously feeds material into the black hole, creating the fuel source for the jets. As matter spirals toward the black hole’s event horizon, a portion of its energy is ejected in the jets. Prabu’s findings reveal remarkable efficiency: 10% of all energy released during the accretion process is transported away by the jets.
Black holes and cosmic evolution
The techniques developed in this research open new possibilities for studying black hole systems. They can now be applied to other black holes, potentially revealing how different systems produce and channel energy through jets. Understanding these mechanisms may help scientists comprehend how black holes influence their surroundings and contribute to galaxy evolution.
The jets from black holes play a significant role in shaping galaxies and regulating star formation on cosmic scales. The energy and material from jets can heat gas surrounding galaxies and limit how efficiently new stars form. With direct measurements of jet power now possible, astronomers can develop more detailed models of how black holes affect their galactic environments.