Using extremely high-resolution simulations of magnetized turbulence, CITA and Princeton Fellow James Beattie and his team show that the turbulent dynamics typical of the interstellar medium (ISM) significantly deviate from widely used classical models. The groundbreaking computer simulation the scholars have developed is described in , the model is the most powerful to date, requiring the computing capability of the SuperMUC-NG supercomputer at the Leibniz Supercomputing Centre in Germany. It directly challenges our understanding of how magnetized turbulence operates in astrophysical environments.

James Beattie, the paper’s lead author, is hopeful the model will provide new insights into the ISM, the magnetism of the Milky Way Galaxy as whole, and astrophysical phenomenon such as star formation and the propagation of cosmic rays.

“This is the first time we can study these phenomena at this level of precision and at these different scales,” Beattie says.

The paper was co-authored with researchers from Princeton University; Australian National University; the Australian Research Council Center of Excellence in All Sky Astrophysics; Universität Heidelberg; the Center for Astrophysics, Harvard & Smithsonian; Harvard University; and the Bavarian Academy of Sciences and Humanities.

Read more on ,��, , .

Contact:
Lyuba Encheva
Communications and Events, CITA
lyuba@cita.utoronto.ca

Supermassive binary black holes in galactic centres are particularly important for studying the most extreme gravitational events in the universe.  As potential multimessenger sources of both gravitational waves and electromagnetic radiation, binaries can be “seen” as light (electromagnetic radiation) and, in coming years, will also be “heard” through the ripples in space and time called gravitational waves.  Space-based detectors targeting these waves will offer additional insight into these systems that can be combined with more traditional observations to deepen our understanding of such unique environments.

“It is an exhilarating time to be studying these supermassive binary systems because we are truly only in the early stages of modeling their interactions with surrounding matter; each step forward is groundbreaking.  As a community we have spent most of our time modeling single black hole sources (like those that have recently been imaged by the Event Horizon Telescope) and in a way this is the next step.  The ground was laid by a handful of pioneering simulations, but we are now able to start pushing towards more realistic regimes and making robust predictions about what we might see,” shares first author and CITA Postdoctoral fellow Dr. Sean Ressler.

Since gravitational wave detectors are not able to precisely locate these supermassive objects, it is imperative to have solid predictions about how such binary systems would appear in the sky. To make such predictions, the authors use high-performance numerical simulations of hot, magnetized gas around binary black holes to identify two ways in which galaxies containing such binaries may shine differently than galaxies containing a single supermassive black hole. The first way involves the collision of the two jets: beams of ultra-fast, highly magnetized outflow accelerated by the rotation of each black hole.  These collisions are very similar to how loops of magnetic field poking through the surface of the sun often collide and generate solar flares. The second way involves “bridges” of magnetic field lines that can spontaneously form between the two black holes.  As the black holes orbit around each other, these bridges get severely twisted until they ultimately snap, releasing a large amount of energy associated with a burst of light.  This is similar to the so-called “coronal mass ejections” in the sun, where bridges form between two moving spots on the solar surface.

“For me, it was most exciting to see the same mechanisms that cause extreme events in the sun show up in binary black hole systems.  On the one hand, you have the most well-studied and (if I may say) important object in space, and on the other, you have something that seems to have appeared straight out of a sci-fi.  But physics is universal, so even the most extreme or remotest parts of the universe are governed by the same physical laws as our local solar system. In fact, this is not the first time that black hole astronomers have learned something from solar astronomers!”, continues Dr. Ressler.

These findings will help future missions identify supermassive black hole binary pairs and link gravitational wave sources with visual counterparts in the sky. As another one of the contributors, CITA National Fellow Luciano Combi, affirms:

“Our new state-of-the-art simulations led and developed by Dr. Ressler represent a major step forward in modeling the plasma around supermassive binary black holes. Thanks to our team’s diverse expertise in magnetohydrodynamics, plasma physics, and curved spacetime, we have devised a few novel emission mechanisms occurring around binaries; surprisingly, these are analogous to phenomena occurring in our sun!  Our hope is that these theoretical results will help detect pairs of giant black holes lurking in the center of galaxies.”

The video sequence above contains a three-dimensional visualization of the two jets in the simulation (in orange and yellow) as they spiral around each other and collide, potentially releasing a large amount of energy in the form of light. (Created by Sean Ressler)

Sean M. Ressler,��Luciano Combi,��Bart Ripperda, Elias R. Most, , ,��,��, DOI 10.3847/2041-8213/ad9eb5, Published 2025 January 22

Contact:
Lyuba Encheva
Communications and Events, CITA
lyuba@cita.utoronto.ca