January 7, 2026
4 min read
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Weird, Wobbling Black Hole Jets Can Shape Entire Galaxies
A wobbling jet from a giant, voracious black hole is suppressing star formation in a distant galaxy—and astronomers have never seen anything quite like it before
An artist’s rendition of a precessing jet erupting from the supermassive black hole at the center of the galaxy VV 340A, based on combined optical, infrared and radio observations.
W. M. Keck Observatory / Adam Makarenko
For decades, astronomers have known that supermassive black holes lurk at the hearts of essentially all large galaxies, occasionally feasting on infalling material and burping out powerful jets. But what’s been less clear is how, exactly, this activity shapes their surrounding galaxies.
Now researchers have found a crucial piece of this galactic puzzle by observing a supermassive black hole shooting out a wobbling jet in the galaxy VV 340A, some 450 million light-years from Earth. The jet acts as a cosmic scale snowplow, pushing away gas that would otherwise fuel the creation of new stars. The result was announced at this year’s winter meeting of the American Astronomical Society in Phoenix, Ariz.
“Conventionally, there are two modes of gas outflows driven by supermassive black holes in galaxies,” says Justin Kader, an astrophysicist at the University of California, Irvine and first author of an associated paper published in Science. In the first so-called radiative mode, a white-hot, incandescent accretion disk of infalling matter forms around a rapidly feeding supermassive black hole, heating the nearby gas. This heated gas then expands and pushes the cooler gas outward. “You can see the gas flowing out of the galaxy in these wide-angle bicone structures,” Kader explains.
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In the second jet-driven mode, a black hole launches firehoselike jets of particles and radiation from its poles, kinetically pushing surrounding gas far out of the galaxy. These jets, though, usually add to a galaxy’s stellar inventory as they jostle and compress gas clouds that then gravitationally collapse to churn out more stars.
In VV 340A, however, Kader and his colleagues found jets from a supermassive black hole doing something distinctly different from either of these two modes.
VV 340A is a spiral galaxy that is merging with another, VV 340B, forming a system collectively called VV 340. In the sky, the pair appear as a celestial exclamation point, with VV 340B’s disk oriented face-on as the exclamation point’s “dot” and VV 340A’s edge-on disk forming the “dash.” For Kader and his colleagues, this edge-on orientation was a stroke of luck, allowing them to more easily probe the inner workings of VV 340A. What they found shooting out of the galaxy’s central black hole wasn’t a standard, straight jet. Instead it was an enigmatic S-shaped structure, demanding deeper investigation to determine its nature.
The “cosmic exclamation point” of VV 340A (top) and VV 340B (bottom), a pair of merging galaxies some 450 light-years from Earth.
NASA, CXC, IfA, NRAO, STScI, and D. Sanders, and A. Evans
Using the infrared eyes of the James Webb Space Telescope, the team could pierce the thick dust veiling VV 340A’s center to discover a massive cloud of superheated, ionized plasma stretching out for nearly 20,000 light-years—far larger than any other black-hole-generated plasma cloud ever seen. Subsequent optical observations at the Keck Observatory in Hawaii confirmed this ionized plasma wasn’t just sitting still but was propelled outward at immense speeds. Finally, radio observations of VV 340A via two radio telescopes, the Karl G. Jansky Very Large Array and the Atacama Large Millimeter Array, showed the plasma was perfectly aligned with the S-shaped jet coming from the black hole.
Kader and his co-authors think this S shape is the hallmark of precession, the same wobble you see in a spinning top as it slows down or in water spewing from the rotating head of a lawn sprinkler. As the black hole spins, its jet doesn’t just point in one direction—it sweeps through space in a conical motion, pushing the star forming gas out of the galaxy at a rate of around 20 solar masses per year. That’s enough, the researchers estimate, to shorten VV 340A’s star-forming lifespan by about 250 million years.
“Twenty solar masses per year is no big deal,” says Andrew Fabian, a British astronomer and former director of the Institute of Astronomy at the University of Cambridge, who was not involved in the study. “But a precessing jet as the driver of gas outflow is something new. It does indeed show that it can significantly move matter around in a spiral galaxy.” One of the still unanswered questions for Kader and his colleagues is what exactly causes the jet’s wobbling motion.
“These wobbling jets are not common, but they have been observed before, mostly in giant elliptical galaxies,” Kader says, noting there are presently thought to be two main drivers for the behavior. One is an accretion disk instability, in which a large clump of gas falling toward the black hole tugs on the disk of material surrounding it, causing it to tilt.
The other, arguably more exciting possibility is that there isn’t just one black hole at the center of the VV 340A but two. A binary pair of supermassive black holes orbiting each other could gravitationally whip the jet around like a garden hose. “To the best of my knowledge, a binary supermassive black hole has not been ever directly observed before. We do not claim we observed that, but it’s one of two possible options,” Kader says.
Higher-resolution radio observations, paired with studies using future observatories such as NASA’s Nancy Grace Roman Space Telescope, could help discern between these two possibilities. In the meantime, the team has flagged another 32 galaxies that are similar to VV 340A for further scrutiny. “What we want to see is the interaction of different gases in the galaxy merger process”, says study co-author Vivian U, also at the University of California, Irvine. “Being able to understand that would allow us to actually answer one of those big-picture questions—to understand the drivers of galaxies’ growth.”
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