The Cosmic Seesaw: Black holes eject material as winds or jets, but not both at once

Astronomers at the University of Warwick have discovered that black holes don’t just consume matter — they manage it, choosing whether to blast it into space as high-speed jets or sweep it away in vast winds.

It’s often imagined that anything drawn toward a black hole is swallowed forever. Yet before crossing the event horizon - the ultimate point of no return - incoming material forms a hot, swirling accretion disk around the black hole. From this disk, surprisingly large amounts of material are in fact expelled back into space.

Black holes expel material from the accretion disk in two primary outflows:

• Relativistic jets: narrow, focused beams of plasma that shoot out from the black hole’s poles at nearly the speed of light, powered by magnetic fields and the black hole’s spin.
• X-ray winds: broader, slower streams of highly ionized gas blown off the surface of the accretion disk by radiation and magnetic pressure.

How and why these two distinct outflows occur, and whether they are connected, has long been one of astrophysics’ many puzzles.

A Tug-of-War in Space

In a new study published in Nature Astronomy, a team led by researchers at the University of Warwick has presented the first clear observational evidence that these two types of outflows are mutually exclusive. When one is active, the other disappears, showing that black holes can’t ‘have it all’.

Dr. Jiachen Jiang, Teaching Fellow, University of Warwick, and one of the study authors said: “We’re seeing what could be described as an energetic tug-of-war inside the black hole’s accretion flow. When the black hole fires off a high-speed plasma jet, the X-ray wind dies down, and when the wind starts up again, the jet vanishes. This tells us something fundamental about how black holes regulate their energy output and interact with their surroundings.”

The team focused on the black hole system 4U 1630−472, which is around ten times the mass of our Sun and undergoes regular outbursts as it draws in material from a nearby companion star.

Using observations from NASA’s NICER X-ray telescope, aboard the International Space Station, and South Africa’s MeerKAT radio telescope, the researchers monitored the black hole over a three-year span. This data showed that the black hole never produced strong winds and strong jets simultaneously, yet the accretion disk, and amount of incoming material, remained consistent.

First author, Dr. Zuobin Zhang, Postdoctoral Research Assistant, Department of Physics, University of Oxford added: “Our observations provide clear evidence that black hole binary systems switch between powerful jets and energetic winds—never producing both simultaneously—highlighting the complex interplay and competition between different forms of black hole outflows.”

A Black Hole in Balance

This seesawing behaviour from the black hole suggests a self-regulating mechanism, in which winds and jets compete for the same energy or mass supply. Remarkably, both types of outflows were found to carry away comparable amounts of mass and energy, suggesting that while the form of the outflow changes, the total outflow rate remains roughly constant.

The discovery challenges several long-held assumptions about how outflows are powered. It indicates that the switch between winds and jets is not simply driven by changes in how much material the black hole is accreting but may instead depend on the magnetic field configuration within the disk - a key factor in shaping how energy is released.

In short, black holes don’t just consume matter, they manage it, deciding whether to blast it into space as a focused jet or sweep it away in vast winds. The balance between winds and jets plays a vital role in regulating how black holes grow, how stars form in nearby regions, and how entire galaxies evolve. This “cosmic seesaw” offers a powerful new window into how these enigmatic objects shape the universe.

ENDS

Notes to Editors

The paper – ‘Evidence of mutually exclusive outflow forms from a black hole X-ray binary’ is published in Nature Astronomy. DOI: 10.1038/s41550-025-02753-x

For more information please contact:

Matt Higgs, PhD | Media & Communications Officer (Press Office)

Email: Matt.Higgs@warwick.ac.uk | Phone: +44(0)7880 175403

Images

Image 1: This artist’s impression shows how the distant quasar P172+18 and its radio jets may have looked. To date (early 2021), this is the most distant quasar with radio jets ever found and it was studied with the help of ESO’s Very Large Telescope. It is so distant that light from it has travelled for about 13 billion years to reach us: we see it as it was when the Universe was only about 780 million years old. Credit: ESO/M. Kornmesser, CC BY 4.0, https://www.eso.org/public/images/eso2103a/

Image 2: Artist’s impression of a galaxy forming stars within powerful outflows of material blasted out from supermassive black holes at its core. Results from ESO’s Very Large Telescope are the first confirmed observations of stars forming in this kind of extreme environment. The discovery has many consequences for understanding galaxy properties and evolution. Credit: ESO/M. Kornmesser, CC BY 4.0, https://www.eso.org/public/images/eso1710a/

Image 3: Combining observations done with ESO's Very Large Telescope and NASA's Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. The black hole blows a huge bubble of hot gas, 1000 light-years across or twice as large and tens of times more powerful than the other such microquasars. The stellar black hole belongs to a binary system as pictured in this artist’s impression. Credit: ESO/L. Calçada/M.Kornmesser, CC BY 4.0, https://www.eso.org/public/images/eso1028a/

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