This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For decades, astronomers have identified collisions between two neutron stars through bursts of gamma rays that can disappear in less than two seconds. But some of these violent encounters may also reveal themselves through X-ray flashes lasting several minutes.
A new study published in Science Bulletin provides evidence for this connection, suggesting that merging neutron stars could be hiding among cosmic flashes whose origins have remained uncertain. Since the launch of the Einstein Probe satellite in January 2024, astronomers have discovered hundreds of bright X-ray flashes from distant galaxies. Known as fast X-ray transients, some of these flashes have been linked to the deaths of massive stars, but others remain unexplained.
Without knowing their distance and the energy they release, astronomers struggle to determine what produced them. Researchers in professor Eleonora Troja's group obtained observations crucial to identifying the source of one such X-ray transient. Following an alert from the Einstein Probe satellite, the team quickly arranged observations with other telescopes, including the European Southern Observatory's Very Large Telescope (VLT) and the Very Large Array, to study the explosion's aftermath.
They believe they witnessed the birth of a magnetar produced by the collision (or merger) of two neutron stars. Neutron stars are the ultradense stellar corpses left behind when massive stars reach the end of their lives. When two neutron stars collide, they send gravitational waves rippling through space.
The light from these events offers a glimpse of what the collision leaves behind. Short gamma-ray bursts have long been the main signpost for these events. "However, if the remnant of the collision is a magnetar, it could keep bursting for longer," said Troja, who is part of the Einstein Probe European collaboration and co-corresponding author of the paper.
"Magnetars are rapidly spinning neutron stars with huge magnetic fields. When they dump their magnetic power into the surroundings, they can make any explosion brighter and longer-lasting. When I saw the X-ray data from this new event, I realized something was up." The event, known as EP250704a/GRB 250704B, was discovered on July 4, 2025, by the SVOM, Insight-HXMT and Einstein Probe satellites.
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