NASA researchers have achieved the most comprehensive simulation yet of the chaotic moments before two city-sized neutron stars collide, revealing potential signals detectable by future observatories. These new simulations, run on the Pleiades supercomputer, explore the tangled magnetospheres – the highly magnetized regions surrounding these dense stars – as they spiral towards merger. The team focused on the final orbits, modeling dramatic shifts in magnetic fields and the resulting high-energy emissions. “Just before neutron stars crash, the highly magnetized, plasma-filled regions around them, called magnetospheres, start to interact strongly,” said lead scientist Dimitrios Skiathas, a graduate student at the University of Patras. Published November 20, 2025, in The Astrophysical Journal, this work promises to unlock new insights into the universe’s most powerful explosions – gamma-ray bursts.
Magnetosphere Interactions During Neutron Star Final Orbits
The final moments of merging neutron stars are proving to be even more dynamically complex than previously understood, thanks to detailed new simulations of the interacting magnetic fields surrounding these collapsing stars. These city-sized objects, packing more mass than our Sun into a sphere roughly 15 miles across, undergo radical changes in their magnetic environments during the final orbits. The simulations, conducted using the Pleiades supercomputer, focused on the period just before impact, revealing a chaotic “rewiring” of magnetic field lines. “In our simulations, the magnetosphere behaves like a magnetic circuit that continually rewires itself as the stars orbit.
Field lines connect, break, and reconnect while currents surge through plasma moving at nearly the speed of light, and the rapidly varying fields can accelerate particles,” explained Constantinos Kalapotharakos at NASA Goddard. The team ran over 100 simulations, each featuring neutron stars with 1.4 solar masses, to explore how varying magnetic field configurations affect electromagnetic energy release. Most simulations covered the last 7.7 milliseconds before merger, allowing for a detailed analysis of the final orbital dance.
The resulting electromagnetic turbulence doesn’t just produce spectacular phenomena like gamma-ray bursts—the most powerful explosions in the universe—but also generates detectable signatures at lower energies. While the highest-energy gamma rays are quickly converted into particles by the intense magnetic fields, lower-energy gamma rays and even X-rays can escape the merging system. “Our work shows that the light emitted by these systems varies greatly in brightness and is not distributed evenly, so a far-away observer’s perspective on the merger matters a great deal,” noted Zorawar Wadiasingh at the University of Maryland, College Park and NASA Goddard.
This directional emission, coupled with the increasing signal strength as the stars approach, presents a tantalizing opportunity for future observatories. Demosthenes Kazanas of Goddard highlights the potential for these findings to inform gravitational wave astronomy, stating, “One value of studies like this is to help us figure out what future observatories might be able to see and should be looking for in both gravitational waves and light.” These magnetic stresses, though secondary to gravity, could even leave an imprint on detectable gravitational wave signals, providing a multi-messenger view of these cataclysmic events.
Pleiades Supercomputer Models 1.4 Solar Mass Neutron Star Systems
Detailed simulations utilizing the Pleiades supercomputer are revealing unprecedented insights into the turbulent environments surrounding merging neutron stars, offering a glimpse into the chaotic dance before cosmic collision. Researchers are focusing on the magnetospheres – the highly magnetized, plasma-filled regions around these dense objects – to identify potential electromagnetic signals that future telescopes might detect. This process isn’t merely a spectacular display; it’s linked to the production of gamma-ray bursts, the most powerful explosions in the universe.
These simulations aren’t just about light; they also compute the electromagnetic forces acting on the stars’ surfaces, even though gravity dominates. “Such behavior could be imprinted on gravitational wave signals that would be detectable in next-generation facilities,” stated Goddard’s Demosthenes Kazanas. However, lower-energy gamma rays and X-rays can escape the system, providing a potential avenue for detection by future observatories.
Simulated Gamma-Ray & X-Ray Emission Predicts Observational Signals
Detailed simulations are now revealing the complex interplay of high-energy light emitted as neutron stars spiral towards collision, offering crucial predictions for future astronomical observations. Researchers used the Pleiades supercomputer to model the final, frantic orbits of these incredibly dense objects, focusing on the behavior of their intensely magnetized plasma environments – known as magnetospheres. The simulations detail how these magnetospheres, interacting with each other, generate detectable signals. The simulations demonstrate that the intensity and direction of this emitted light are highly variable, dependent on the observer’s perspective and the alignment of the stars’ magnetic fields.
Furthermore, the team computed electromagnetic forces on the stars’ surfaces, noting that while gravity dominates, magnetic stresses could influence the final merger dynamics and potentially imprint themselves on detectable gravitational wave signals. This predictive capability is critical, as future observatories – both ground and space-based – prepare to hunt for these pre-merger electromagnetic signals, complementing gravitational wave detections.
Magnetic Field Rewiring & Particle Acceleration in Mergers
Newly detailed simulations are revealing the extraordinary electromagnetic environment surrounding neutron stars as they spiral towards collision, offering insights into the origins of powerful gamma-ray bursts and potential new avenues for multi-messenger astronomy. Researchers have, for the first time, modeled the complex interplay of magnetic fields – the magnetospheres – in the crucial moments preceding merger, identifying potential signals detectable by future observatories. The simulations, utilizing the Pleiades supercomputer, focused on the last 7.7 milliseconds before impact, allowing for unprecedented resolution of these dynamic processes. The research highlights how magnetic field lines connecting the two neutron stars undergo constant transformation.
This isn’t merely a structural rearrangement; it’s an engine for particle acceleration. The resulting acceleration can boost particles to energies exceeding those achievable in terrestrial particle accelerators. These energetic processes generate a spectrum of electromagnetic radiation, including telltale X-rays and gamma rays.
In our simulations, the magnetosphere behaves like a magnetic circuit that continually rewires itself as the stars orbit. Field lines connect, break, and reconnect while currents surge through plasma moving at nearly the speed of light, and the rapidly varying fields can accelerate particles.
Constantinos Kalapotharakos at NASA Goddard
