Researchers Reveal Insights into Supermassive Black Holes, Binary Neutron Star Mergers

While scientists know supermassive black holes collide, these events have remained invisible to telescopes. Researchers at the Rochester Institute of Technology (RIT) have now identified a specific spike in light that occurs at the moment of merger, providing the roadmap needed to finally observe these cosmic giants in action.

Led by Lorenzo Ennoggi ‘25 Ph.D. (astrophysical sciences and technology) and his advisor Manuela Campanelli, distinguished professor of astrophysics, members of RIT’s Center for Computational Relativity and Gravitation (CCRG) have published two papers in American Physical Society journals.

In the first paper, the team looked at two spinning black holes accreting gas and generating powerful electromagnetic signals. Through complex simulations, it was confirmed that there is a steady decrease in the system’s luminosity, but then at the time of merger, there is an abrupt spike.

“People were not able to do this simulation with the full physics that Lorenzo has been able to include, so they were not getting this rise in luminosity at the merger,” Campanelli explained. “What Lorenzo has discovered is that there is a bump at the merger, and the bump is correlated between both the jet and the light from the disk. That bump is important because it will allow mergers to be identified for the first time.”

Campanelli further explained that while it is known that galaxies collide and their central black holes collide, they have not been observed. Getting the right signal for these events, as Ennoggi calculated, is needed to be able to identify the mergers and then observe them.

“I had to repeat the simulations quite a few times,” said Ennoggi. “When I finally had something that worked and we managed to find something of relevance from the physics point-of-view, I was very happy.”

Current astrophysical sciences and technology Ph.D. student, also advised by Campanelli, and co-author Maria Chiara de Simone further explained, “We are in the process of getting ready to help in observations because the gravitational wave emission and the electromagnetic emission together help with localization so we can get more information about galaxy evolution in a broader aspect.”

This research was supported by computational resources at the Texas Advanced Computing Center (TACC), including the Frontera and Vista supercomputers, and by additional resources from the Rochester Institute of Technology’s BlueSky, Green Prairies, and Lagoon clusters.

"I would love for the public to understand that supercomputers act as the ultimate ’virtual laboratories' for the extreme universe,” Campanelli said. “High performance computing provides the only method we have to solve the fundamental equations governing gravity and matter in these environments.” 

Seeing the Light From Black Holes

In the second paper, researchers conducted simulations that may provide a new way to identify supermassive black hole mergers through photon emissions.
Black hole mergers are identified primarily by gravitational waves, but these events also radiate photons from thermal gas and photons from relativistic electrons energized by relativistic jets. The simulations conducted showed that during a merger of two black holes with the same mass and spin, photon radiation decreases as the black holes are drawn together, but the light increases sharply during mergers. Such a distinct signature could help identify such mergers.

High performance computing provides the only method we have to solve the fundamental equations governing gravity and matter in these environments.

Computational resources were provided by TACC’s Frontera supercomputer, with additional support from RIT’s BlueSky, Green Prairies, and Lagoon clusters. The publications capped four years of Ennoggi’s Ph.D. research. He moved back to Italy after graduating from RIT and now works in high performance computing applied to oil and gas. De Simone is continuing his work on her Ph.D. journey.

“I’m continuing Lorenzo’s work and extending the parameter space of our simulations,” de Simone said. “The idea is to produce simulations that help us with observations. We can work together with the observation side of the astrophysics world and get more exciting results.”

Gamma-ray Burst Mysteries From Star Mergers

Campanelli and colleagues also recently published findings that shed new light on the long-standing question of how binary neutron star mergers generate short gamma-ray bursts (GRBs), among the most energetic phenomena in the universe.

By employing an unprecedentedly low-density numerical atmosphere, their simulations demonstrated that a metastable massive neutron star remnant collapsing into a black hole 25–50 milliseconds post-merger successfully launch incipient jets. These outflows exhibit terminal Lorentz factors and Poynting-flux luminosities consistent with those observed in short GRBs.

"This is a crucial finding because it highlights the critical role of the highly dynamic post-merger environment in shaping jet propagation, directly linking our computational models to the violent bursts telescopes observe in the night sky," Campanelli said.

Simulating these events proved to be an immense undertaking, requiring the coupling of Numerical Relativity to solve the full Einstein equations with 3D General Relativistic Magnetohydrodynamics (GRMHD) across vast spatial and temporal scales. 

Cosmic Heavy Lifting From Frontera, Vista, Horizon Supercomputers

"For supermassive black hole binaries—as explored in our recent Physical Review Letters paper and companion work on post-merger recoil—a major challenge is accurately modeling incredibly complex gas dynamics, circumbinary disks, and radiation transport," Campanelli explained. The challenges involved tracking intricate fluid mechanics, such as gas "sloshing" between minidisks, and predicting the sudden luminous flares that occur at the exact moment of merger. 

"National Science Foundation (NSF)-funded supercomputers Frontera and Vista provided the essential, heavy-lifting CPU and GPU architectures necessary to handle these high-resolution, multi-scale computations,” she said. “Without their immense processing power and memory capacity, smoothly tracking these systems from the long inspiral phase completely through to post-merger relaxation would be impossible.”

The team's work will continue on Horizon, the flagship system of the U.S. NSF Leadership Class Computing Facility​, as it enters its early user phase at TACC in summer 2026. 

"We are continuously developing open-source, exascale-optimized frameworks (like the Einstein Toolkit) to push these models further, and the transition to Horizon will be a true gamechanger,” Campanelli concluded. “It will enable us to explore a vastly expanded parameter space—including highly unequal mass ratios, extreme black hole spins, and orbital eccentricities—at unprecedented resolutions and over much longer physical timescales. Horizon’s capabilities will allow us to drastically improve the precision of our synthetic multi-messenger predictions, allowing us to transition from modeling idealized scenarios to creating highly accurate templates for specific, real-world astronomical observations.”

Adapted from a press release by Mollie Radzinski, RIT.