The secret energy inside every black hole is more powerful than we thought

Researchers have discovered that black holes can pump and release huge amounts of energy through magnetic fields and magnetized accretion disks, which could change our understanding of galaxy formation and the evolution of the universe.

Discovering the power of black holes

Black holes have long fascinated scientists—not just as cosmic vacuum cleaners but as powerful energy engines that can suck up and redistribute vast amounts of energy. These mysterious giants are often surrounded by swirling disks of gas and dust, called accretion disks. When these disks become strongly magnetized, they can act as galactic powerhouses, drawing energy from the black hole’s rotation through a process called the Blanford-Zenaik (BZ) effect.

Researchers believe the BZ effect is the main mechanism driving this energy pumping, but many questions remain. It is still unclear what determines how much energy is directed into powerful jets—streams of particles and radiation that shoot out from the black hole's poles—or is lost instead as heat.

Advanced simulations to decipher the physics of black holes

To explore these mysteries, JILA researchers Prason Dang, Mitch Biegelman, and Jason Dexter turned to advanced computer simulations. By modeling black holes with thin, highly magnetized accretion disks, they sought to uncover the physics underlying these powerful systems.

Their findings, published in The Astrophysical Journal on February 14, provide important insights into the dynamics of black holes and may reshape our understanding of their influence on galaxy formation.

"It has long been known that infalling gas can suck energy from a black hole," Dexter explains. "We usually assume that this is important for driving jets. Using more precise calculations, Frason has shown that there is much more energy being sucked in than previously known. This energy may be radiated as light, or it may be causing the gas to flow outward. Either way, sucked-in rotational energy may be an important source of energy for illuminating the regions near the black hole's event horizon."

Comparison of black holes

For decades, scientists have been studying black holes and their interactions with the gas and magnetic fields around them to understand how they drive some of the most energetic phenomena in the universe. Early research focused primarily on sources that are low-luminosity black holes with quasi-spherical accretion flows because these systems are relatively easy to model and fit many of the jets that have been observed.

But black holes with high luminosity and thinner, denser magnetized disks pose a unique challenge. These systems are theoretically unstable due to an imbalance between heating and cooling.

But previous studies, including those by Mitch Biegelman, suggest that strong magnetic fields may stabilize these thin disks, but their role in extracting energy and generating jets remains unclear under these conditions.

"We wanted to understand how energy pumping works in these highly magnetized environments," explains Dang.

Simulating magnetized flows around black holes

The team used advanced computer simulations to study this phenomenon, specifically a type of model called GRMHD. The GRMHD model acts as a computational framework that simulates the behavior of magnetized plasma in the curved spacetime around a black hole, combining the physics of magnetic fields, fluid dynamics, and Einstein's general theory of relativity to capture the complex interactions in these extreme environments. Using the framework, the researchers observed the interactions of magnetic fields with black holes spinning at different speeds.

for the scientific article

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