A wobbling black hole jet is stripping a galaxy of star-forming gas

Astronomers led by Justin Kader have now observed this process in action in a nearby active galaxy known as VV 340a. Their findings show that a jet launched by the galaxy's central black hole is driving a large-scale gas outflow that is strong enough to influence the galaxy's future star formation.

A Jet That Pushes Gas Outward

VV 340a contains a supermassive black hole that is actively feeding, making it an ideal place to study how black holes interact with their host galaxies. Using observations across infrared, optical, radio, and sub-millimeter wavelengths, the research team was able to trace both the jet and the gas being expelled from the galaxy.

The observations came from several major facilities, including the James Webb Space Telescope, the Keck-II telescope, the Karl G. Jansky Very Large Array, and the Atacama Large Millimeter/submillimeter Array. Each telescope provided a different piece of the puzzle, allowing the team to build a more complete picture of how energy from the black hole moves through the galaxy.

The data show that the jet ionizes gas and pushes it away from the galaxy's center as it travels outward. The researchers estimate that gas is being expelled at a rate of 19.4 ± 7.9 solar masses per year. That is roughly the mass of 19 suns lost annually, an amount large enough to disrupt the supply of material needed to form new stars.

A Wobbling Jet on a Galactic Scale

By combining the observations with computer modeling, the team discovered that the jet from VV 340a does not move in a straight line. Instead, it slowly traces out a cone-shaped motion known as precession. This kind of motion is similar to the gentle wobble of a spinning top as it turns.

At large scales, radio data reveal that the jet forms a helical pattern as it propagates through the galaxy. According to the researchers, this is the first time a precessing radio jet spanning kiloparsec scales has been observed in a disk galaxy. The unusual motion helps the jet interact with more of the surrounding gas, making it more effective at pushing material outward.

Extremely Hot and Unusual Gas

The gas being driven out of VV 340a is highly energized and strongly ionized, meaning its atoms have lost electrons due to extreme conditions. Astronomers refer to this type of material as coronal line gas, a term borrowed from studies of the sun's outer atmosphere. In most galaxies, this kind of gas is found very close to the black hole and rarely extends far into the host galaxy.

In VV 340a, however, the coronal gas reaches much farther than usual. Infrared observations from Webb were especially important in revealing this structure. The galaxy contains large amounts of dust that block visible light, but infrared wavelengths can pass through that dust, exposing energetic processes hidden from traditional telescopes.

The team suggests that as the jet flows outward, it couples with gas in the galaxy and heats it to extreme temperatures while pushing it away from the center. This combination of heating and removal makes the gas unusable for forming new stars.

Why This Matters for Galaxy Evolution

Star formation depends on a steady supply of cool gas. When a black hole jet heats that gas or expels it entirely, the galaxy's ability to produce new stars can drop sharply. In VV 340a, the measured outflow rate is high enough to significantly limit star formation over time, according to the researchers.

Jets like the one seen in VV 340a are not currently active in the Milky Way, although there is evidence that our own galaxy's central black hole may have gone through a more active phase millions of years ago. By studying systems like VV 340a, astronomers hope to better understand how black holes regulate the growth and evolution of galaxies across the universe.

Now that the team has identified a rare, galaxy-scale wobbling jet and its associated gas outflow, they plan to search for similar examples in other galaxies. Finding more cases like this could help clarify how common these powerful interactions are, and how strongly they shape the life cycles of galaxies like our own.