Earth-Sized Telescope Measures Wind-Bent Cygnus X-1 Jets at 10,000 Suns’ Power

A stellar wind supplied the measuring tool. As jets streamed from the black hole in Cygnus X-1, wind from its supergiant companion pushed those outflows away from their original paths. Researchers measured the deflection with an Earth-sized virtual radio telescope and calculated that the jets carried instantaneous power equivalent to the output of about 10,000 Suns.

The Curtin University and University of Oxford research, published in Nature Astronomy on April 16, 2026, also put the jet material’s speed at approximately 150,000 kilometers per second, or 93,200 miles per second. That is roughly half the speed of light. The result turns an apparent distortion in radio images into a direct constraint on how an accreting black hole distributes energy.

The bend revealed the force behind the jets

Cygnus X-1 is a binary system containing the first black hole whose existence was confirmed. The black hole and its massive companion move around their shared orbit while material falling toward the black hole releases energy. Some of that energy emerges in narrow jets rather than remaining near the accreting object.

Those jets do not travel through an undisturbed environment. The companion star produces powerful winds that buffet them as the two objects orbit. The researchers compared the effect with strong wind pushing and distorting a stream of water from a fountain. A more powerful jet resists that sideways pressure more effectively; a less powerful one bends farther under the same wind.

That relationship allowed the team to work backward from the observed curvature. By accounting for the stellar wind and measuring how far the jets moved from their expected paths, the researchers derived the jets’ power at the time of observation. Lead author Dr. Steve Prabu called their changing appearance “dancing jets.”

Capturing that motion required more resolution than a single conventional radio dish could provide. The team used interferometry, combining observations from radio telescopes separated by large distances so that they operated as an Earth-scale virtual instrument. A sequence of reconstructed images then showed how the jet positions changed over time rather than providing only one static view.

An instantaneous measurement closes a timing gap

Earlier methods could estimate average jet power over periods spanning thousands or even millions of years. Such long-term averages are difficult to compare with X-ray emission produced by matter falling toward a black hole at a particular moment. The wind-bending method instead yielded an instantaneous jet-power estimate, putting the outflow and the contemporary accretion activity on a more comparable timescale.

From that comparison, the researchers concluded that the jets carry away approximately 10% of the energy released as matter falls toward the black hole. Theoretical models had commonly used a relationship around that level, but obtaining a direct observational check had been difficult. Here, the wind that complicated the jets’ path also made the energy transfer measurable.

The 10% figure describes the share of released accretion energy carried by the jets, not the fraction of incoming matter physically ejected. It gives modelers an observational anchor for estimating how efficiently a black-hole system channels available energy into fast outflows and its surrounding environment.

The result comes from one stellar-mass black-hole binary, so it does not by itself establish how every black hole affects a galaxy. Its practical value is narrower and more concrete: Cygnus X-1 now supplies a directly measured reference point for jet speed, instantaneous power and energy share. Future radio observations can test how well that reference carries across black holes of very different masses.

That work will gain scale as new radio facilities come online. The Square Kilometre Array Observatory, under construction in Western Australia and South Africa, is expected to detect jets from black holes in millions of distant galaxies. Cygnus X-1’s wind-bent outflows provide a calibration point for interpreting those detections derived from jets moving at half light speed and carrying the power of roughly 10,000 Suns.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.