Simulations reveal surprising electron temperatures near M87 black hole’s event horizon

The first images of Black Hole amazed the world in 2019, with titles announcing evidence of a brilliant object in the form of the center of the Galaxy Messier 87 (M87 —55 million light years from the earth. Super-manager simulations now help scientists refine the horizon of the environment beyond the “shadow” of a black hole.

“Since we made this first image of a black hole, there has been a lot of work by trying to understand the right environment around the black hole,” said Andrew Chael, associate researcher at Princeton University and a member of Princeton Gravity Initiative.

Chael is part of the collaboration of the Horizon Event (EHT) telescopes, which connects telescopes from around the world to form a mega telescope about the size of the earth. The EHT uses a technique called very long basic interferometry, a type of astronomical interferometry used in astronomy radio which compares telescope signals to assemble images that resolve the black M87 hole.

It is shown in the image of the black hole is light of hot electrons which spiral around the surrounding magnetic field lines and produce synchrotron radiation.

“We want to understand the nature of the particles of this plasma that the black hole eats, and the details of the magnetic fields coming with the plasma which, in M87, launches huge luminous jets of subatomic particles,” said Chael.

Like a tag, the jets point out the possible presence of a black hole in the center of the M87 galaxy while it spits particles from the thousands of light years from the source.

Use of supercomputers to simulate plasma of black hole, magnetism and gravity

Around the world, scientists exploit the power of supercalculators to disentangle one of the most extreme environments in the universe: space around black holes.

The Chael’s research group is one of those who use advanced simulations to model the dynamic interaction between high energy plasma, powerful magnetic fields and the overwhelming attraction of gravity near these cosmic giants. These forces do not act in isolation – they interact in a complex way and focused on feedback which allow black holes to consume the surrounding material, to launch jets on large distances and to emit the brilliant radiation captured by the Horizon Event telescope.

The recent advances of Chael in his simulation techniques are reported in his study published in February 2025 in the Monthly opinion from the Royal Astronomical Society. They go beyond the typical simulations which treat the electrically loaded particles of protons and electrons in the plasma surrounding the black hole as a single liquid.

“This article is a first attempt to use a more advanced and more expensive technique in calculation to directly model these species of distinct particles of electrons and protons to try to understand how they interact, and in particular, what is the relative temperature of the two,” he explained.

The relative temperature between electrons and protons determines the brightness and other properties of the image of the black hole.

“What we have found through the simulations is that the temperature of the electrons is much higher than what is generally considered to be the case in M87. We are unable to reproduce the low polarization, which is one of the main constraints to understand what the temperature of the plasma is around the black hole,” said Chael.

The results highlight a fundamental tension between current models of electronic heating in plasma physics and the observation constraints provided by the EHT.

“It seems that the black hole of M87 has electrons which are approximately 100 times fresher than protons. It is an interesting direction to proceed,” said Chael.

Chael completed its black holes simulations on the Stampede2 and later the Stampede3 superordinators of Texas Advanced Computing Center (TACC), with allowances awarded by the Coordination Coordination Program for the Advanced Cyberinfrastructure of the National Science Foundation (NSF).

“I use XSede and now access TACC resources since higher education,” said Chael. “This is the main center of academic supercalculculculculculculculculculculculculculis that I carried out for my research. These systems were both extremely easy to use with my code,” said Chael.

A series of 11 Magnetohydrodynamics general relativistic simulations (GRMHDS) which cover a range of different laps of black hole have been completed on Stampede2 and Stampede3 for this study. The decomposition, “general relativist” explains the strong severity of the space-time of black hole. “Magnetohydrodynamic” adopts an approach to fluid dynamics of the magnetic fields of the black hole.

More research to come

Several years ago EHT data that has not yet been picturessed, and he hopes to make a film that follows his evolution over time.

In January 2025, Chael and his EHT collaborators published a study comparing the image of the black M87 hole captured by the EHT to a wide range of simulations. To support this work, he received IT Allocations to access the STAMPEDE2 Supercalculators and Jetsstream, and he carried out simulations on the Frontera system funded by the NSF in TACC.

High resolution simulations have revealed that if the shadow of the black hole remains remarkably coherent in size and general structure from year to year, it is far from static. In addition, the brightest point of the ring moves over time, driven by a turbulent mixture and dynamic plasma flows near the horizon of the event. While different regions of gas heat or cool due to these chaotic processes, the appearance of the black hole evolves subtly but in a measurable way.

“Black holes are extremely complicated environments,” said Chael. “The best available tools that we have are the simulations of supercalculculculculculculculculculculculculculculculculk.