Turbulence in black hole accretion disks simulated

Aug. 30 () –

Next-generation supercomputers have yielded the highest-resolution simulations of turbulence in structures called accretion disks that surround black holes.

An accretion disk, as its name suggests, is a disk-shaped gas that spirals into a central black hole.

There is great interest in studying the unique and extreme properties of black holes. However, Black holes do not allow light to escape and therefore cannot be perceived directly by telescopes. To probe and study black holes, we observe how they affect their surroundings. Accretion disks are one such way to indirectly observe the effects of black holes, as they emit electromagnetic radiation that can be seen with telescopes.

“Accurate simulation of the behavior of accretion disks significantly improves our understanding of the physical phenomena surrounding black holes“, he explains in a statement Yohei Kawazura, from Tohoku University and a member of the research team, said: “It provides crucial information for interpreting observational data from the Event Horizon Telescope.”

The researchers used supercomputers such as RIKEN’s “Fugaku” (the fastest computer in the world until 2022) and NAOJ’s (National Astronomical Observatories of Japan) “ATERUI II” to perform unprecedented high-resolution simulations. Although numerical simulations of accretion disks have already been performed, none have observed the inertial range due to a lack of computational resources.

This study was the first to successfully reproduce the “inertial range” which connects large and small eddies in the turbulence of accretion disks.

“Slow magnetosonic waves” were also found to dominate this range.. This finding explains why ions are selectively heated in accretion disks. Turbulent electromagnetic fields in accretion disks interact with charged particles, potentially accelerating some to extremely high energies.

In magnetohydronomics, magnetosonic waves (slow and fast) and Alfvén waves constitute the basic wave types. Slow magnetosonic waves were found to dominate the inertial range, carrying about twice as much energy as Alfvén waves. The research also highlights a fundamental difference between accretion disk turbulence and solar wind turbulence, where Alfvén waves dominate.

This breakthrough is expected to improve the physical interpretation of observational data from radio telescopes focused on regions close to black holes, according to the authors, whose findings are published in Science Advances.