New observations from the James Webb Space Telescope, or JWST, are giving astronomers their clearest look yet at how supermassive black holes obtain the gas they need to grow.
The images reveal long strands of gas linking a galaxy’s hot outer atmosphere to a rapidly rotating disk surrounding its central black hole. That disk acts as the final reservoir of material before gas falls inward and fuels the black hole.
An international research team led by the Université de Montréal, with contributions from Michigan State University, carried out the observations and analyzed the results. Their findings, published in the July 14 issue of The Astrophysical Journal Letters, help address a question that has challenged astronomers for decades.
“JWST observations are offering us thousands of new facts and measurements, and I can report it’s a lot to absorb,” said Megan Donahue, MSU University Distinguished Professor of physics and astronomy. “We are all working together to solve the astrophysics questions about how these black holes get their fuel and how they interact with their host galaxy.”
How Supermassive Black Holes Affect Galaxies
Nearly every large galaxy contains a supermassive black hole, or SMBH, at its center. These objects can be millions or billions of times more massive than the sun.
A black hole itself does not emit light. However, when large amounts of gas and dust fall toward it, the material heats up and creates an extremely bright and energetic region. Astronomers call this an active galactic nucleus, or AGN.
An active black hole can behave like a powerful cosmic engine. It may launch enormous jets that carry energy far beyond the center of the galaxy. These jets can heat surrounding gas, slow the formation of new stars, and influence how the galaxy changes over billions of years.
That creates a long-standing puzzle. If the jets heat the nearby gas, they should make it harder for that gas to cool and fall toward the black hole. In theory, the black hole should eventually cut off its own food supply.
Yet many supermassive black holes continue feeding.
A Possible Black Hole Fuel Cycle
The leading explanation is that the system regulates itself.
Gas heated by the black hole’s activity may eventually cool again. As it loses energy, it can condense into long, narrow structures known as filaments. These streams of cooler gas may then fall back toward the galaxy’s center and replenish the black hole’s fuel supply.
To investigate this process, the researchers used JWST to study NGC 4696, the largest central galaxy in the Centaurus Cluster. The cluster is a dense collection of galaxies about 145 million light-years from Earth and is considered one of the best places to examine how active galactic nuclei interact with their surroundings.
The team observed NGC 4696 for nearly eight hours using JWST’s NIRSpec instrument. NIRSpec separates infrared light into its component wavelengths, allowing scientists to determine how gas is moving, what it is made of, and how its properties vary across a region.
The resulting maps traced gas motion deep within the black hole’s sphere of influence. This is the area where the black hole’s gravity dominates the movement of nearby material.
JWST resolved structures as small as roughly 30 light-years across. Although that distance is enormous by human standards, it is a remarkably fine level of detail inside a galaxy that spans hundreds of thousands of light-years.
Gas Pouring Into a Spinning Disk
The observations showed that an S-shaped structure near the galaxy’s center is actually a rotating disk of gas around the supermassive black hole.
The disk stretches nearly 800 light-years across, and some of the material inside it is moving at speeds of up to 600 kilometers per second.
Most importantly, the disk appears to be physically connected to one of the galaxy’s large inward-flowing gas filaments. The JWST data show gas traveling along the filament and entering the rotating disk that supplies material to the black hole.
This connection provides some of the strongest observational evidence yet that cool gas filaments can act as feeding channels for supermassive black holes.
Completing the Black Hole Feedback Loop
The findings help fill in the missing steps of a larger cycle.
First, jets launched by the active black hole inject energy into the surrounding galactic gas. Over time, portions of that gas cool, become unstable, and collapse into thin filaments. Some of these structures are only a few hundred light-years wide but extend for thousands of light-years.
As the gas falls inward, magnetic forces may help reduce its rotation and guide it toward the center. The material then collects in a spinning disk around the black hole.
The disk feeds the black hole, the black hole powers new jets, and those jets heat the surrounding gas once again.
In this way, the black hole may help create the conditions that eventually provide its next supply of fuel.
Simulations Support the JWST Observations
The researchers also used advanced computer simulations to test whether this explanation could reproduce the behavior seen by JWST.
The simulated gas moved and condensed in ways that closely resembled the observed system. That agreement provides independent support for the idea that cooling gas, magnetic fields, and black hole jets work together in a self-regulating cycle.
“It’s been really exciting to participate in this project,” MSU Physics and Astronomy Professor Mark Voit said. “Calculations done by our Michigan State group predict that magnetic fields should help feed the universe’s biggest black holes by channeling cool gas toward them, and it’s amazing to see that happening in these JWST images.”