Black holes are among the most mysterious objects in the universe. They are famous for their strong gravity, which pulls in everything that gets too close, even light. But black holes do much more than just swallow matter. Some of them also produce huge amounts of energy, powerful jets, and fast-moving winds that travel across space. These energetic black holes can shine brighter than entire galaxies.
For many years, scientists have tried to understand why some black holes are much more powerful than others. Is it because they are heavier? Is it because they spin faster? Or is it because they are pulling in more gas?
A new study by Kwan and his team has helped answer these questions. Using advanced computer simulations, the researchers found that a black hole's spin and the amount of material falling into it are the two biggest factors that control its power. Surprisingly, the black hole's mass had very little effect in the range they studied.
What Happens Around a Black Hole?
A black hole is surrounded by gas and dust from nearby space. This material does not fall straight into the black hole. Instead, it forms a fast-spinning disk called an accretion disk.
As the gas spins, it becomes extremely hot and releases huge amounts of light, X-rays, and other forms of energy. Scientists have long believed there is a limit to how bright a black hole can become. This limit is called the Eddington limit.
If the black hole becomes brighter than this limit, the pressure from its radiation should push away the incoming gas, making it difficult for more material to fall in.
However, astronomers have discovered many black holes that appear much brighter than this limit. These are called super-Eddington black holes, and scientists wanted to know how they are able to keep feeding while producing so much energy.
Running Powerful Computer Simulations
To study this mystery, Kwan and his team created 32 detailed computer simulations of black holes.
They tested black holes with masses of:
5 times the mass of the Sun
15 times the mass of the Sun
30 times the mass of the Sun
They also compared two types of black holes:
Black holes that do not spin.
Black holes that spin very fast.
The team also changed how much gas was flowing toward each black hole, from low feeding rates to extremely high ones.
This allowed them to compare many different situations and understand which factors really matter.
Black Hole Mass Was Not the Main Factor
One of the biggest surprises was that the mass of the black hole made almost no difference.
Whether the black hole was five, fifteen, or thirty times heavier than the Sun, the results were almost the same.
Instead, the researchers found that two things controlled the black hole's behavior:
How fast it spins.
How much gas falls toward it.
These two factors had a much bigger effect than mass.
Black Holes Do Not Eat Everything
Many people imagine that black holes swallow everything around them.
The simulations showed that this is not true.
Only about 10% to 40% of the gas actually fell into the black hole.
The remaining 60% to 90% was pushed away by powerful winds before it could reach the black hole.
The faster gas was supplied, the smaller the amount that was actually swallowed.
Fast-spinning black holes also threw away more gas than black holes that were not spinning.
This means black holes actually eject much more material than they consume.
Strong Magnetic Fields Play an Important Role
The study focused on black holes surrounded by very strong magnetic fields.
These magnetic fields become so powerful that they can slow down the flow of gas near the black hole. Scientists call this a Magnetically Arrested Disk (MAD).
Although the magnetic field slows the gas, it also helps produce powerful winds and high-speed jets.
If the black hole is spinning quickly, the magnetic field can even take energy from the black hole's rotation and use it to launch jets that travel close to the speed of light.
This makes spinning black holes much more energetic than those that are not spinning.
Fast-Spinning Black Holes Produce More Energy
The researchers found a clear difference between spinning and non-spinning black holes.
Black holes that did not spin produced steady winds and moderate amounts of radiation.
Their energy output stayed almost the same even when more gas was supplied.
Fast-spinning black holes behaved very differently.
As more gas flowed into the system:
Their winds became much stronger.
They produced more radiation.
Their magnetic energy increased.
Their jets became much more powerful.
In simple words, a rapidly spinning black hole is much better at turning falling gas into energy.
Jets Cannot Keep Growing Forever
The simulations also showed that black hole jets have a limit.
As the feeding rate increased, the jets became stronger.
However, after reaching a certain point, the jet power stopped increasing.
This happens because the magnetic field around the black hole cannot keep getting stronger forever.
After this point, extra gas mainly creates stronger winds instead of bigger jets.
Black Holes Can Look Brighter Than They Really Are
Another exciting discovery involved the way black holes send out light.
The radiation is not released equally in every direction.
Instead, much of it escapes through narrow openings above and below the black hole.
If Earth happens to be in the path of one of these beams, the black hole appears much brighter than it actually is.
For rapidly spinning black holes, this effect can make them appear more than 100 times brighter than expected.
This helps explain why some black holes seem to break the normal brightness limit.
Why This Study Is Important
These findings help explain some of the brightest objects in the universe, including Ultraluminous X-ray Sources (ULXs).
The study also shows that black holes can have a huge effect on their surroundings.
The powerful winds and jets they produce can push away nearby gas, shape clouds in space, and influence the formation of new stars.
The researchers also found that very fast winds moving at more than 30% of the speed of light are likely produced by rapidly spinning black holes.
This gives astronomers a new way to estimate how fast a black hole is spinning.
Looking to the Future
Although the simulations are among the best ever performed, scientists say there is still more to learn.
Future studies will include even more realistic conditions, better models of radiation, and larger simulations.
New telescopes being built today will also help scientists compare these predictions with real observations of black holes across the universe.
Conclusion
The new study by Kwan and his team provides one of the clearest explanations yet for why some black holes are much more powerful than others.
The researchers found that black hole spin is the most important factor in determining how efficiently a black hole produces energy, while the amount of gas falling into it controls the total power it can generate. Surprisingly, the black hole's mass made very little difference in the range studied.
The simulations also revealed that black holes throw away most of the gas they receive, produce powerful winds and jets, and can appear much brighter when viewed from the right direction.
These discoveries improve our understanding of some of the universe's most extreme objects and will help astronomers study black holes more accurately in the years ahead.
Reference: Tom Man Kwan, Lixin Dai, Cheuk Kwan Kan, Zepei Xing, Tassos Fragos, Matthew Middleton, Tao Ji, Feng Yuan, "Strongly Magnetized Super-Eddington Accretion: How Spin and Accretion Rate Regulate Energy Output and Mass Loss", Arxiv, 2026. https://arxiv.org/abs/2607.28919
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