Astronomers detect 'heartbeat' of a neutron star in a cosmic explosion
For the first time, an international team of researchers has captured direct evidence of the “heartbeat” of a newborn neutron star within a distant gamma-ray burst (GRB). This groundbreaking discovery provides crucial proof that at least some of the cosmos' most explosive events are powered by rapidly spinning, highly magnetic stellar cores known as magnetars rather than black holes.
A stellar heartbeat in GRB 230307A
This discovery centers on GRB 230307A, detected on March 7, 2023, the second-brightest gamma-ray burst ever recorded. Scientists from the University of Hong Kong (HKU), Nanjing University, and the Institute of High Energy Physics of the Chinese Academy of Sciences identified a fleeting yet highly consistent oscillation at 909 Hz, lasting only 160 milliseconds. This marks the first time humanity has directly observed periodic signals from a millisecond magnetar within a gamma-ray burst.
The research team analyzed over 600,000 datasets collected by China’s GECAM satellites and NASA's Fermi Gamma-ray Burst Monitor. The signal, spinning nearly a thousand times per second, points to the birth of a magnetar, a rapidly rotating neutron star with an ultra-powerful magnetic field.
“This is the first time humanity has directly observed a periodic signal from a millisecond magnetar within a gamma-ray burst,” said Run-Chao Chen, a doctoral student at Nanjing University and lead author of the study. “It’s like hearing the first heartbeat of a newly born star.”
These findings, published in Nature Astronomy in September 2025, represent a significant milestone in astrophysics, offering the clearest evidence yet that magnetars can drive some of the brightest explosions in the universe.
Solving a cosmic mystery
Gamma-ray bursts are the brightest explosions known, briefly outshining entire galaxies. For decades, scientists have debated whether the remnants of stellar collisions collapse immediately into black holes or survive as highly magnetized neutron stars. This discovery helps resolve that debate, showing that newborn magnetars can indeed survive compact star mergers and act as powerful cosmic engines.
“This hidden ‘heartbeat’ confirms that some gamma-ray bursts are not powered by black holes but by newborn magnetars,” explained Professor Bing Zhang, a physicist at the University of Hong Kong and co-author of the study.
The fleeting duration of the signal raised questions about its brevity. Zhang proposed a theoretical explanation: “The magnetar’s rapid rotation imprints a periodic signal on the gamma-ray jet via its magnetic field. However, as the jet evolves quickly, this signal appears only when the emission becomes briefly asymmetric.”
This interpretation suggests that GRB 230307A was powered by a Poynting-flux-dominated jet, an energy flow primarily guided by magnetic fields rather than matter. These concepts, theorized by Professor Zhang more than a decade ago, find strong support in this discovery.
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