Astronomers have identified a connection between neutron star mergers and long-lasting X-ray flashes, a discovery that may explain previously mysterious cosmic events. While neutron star collisions have historically been linked to gamma-ray bursts lasting less than two seconds, a study published in Science Bulletin confirms that some of these mergers produce X-ray emissions visible for nearly ten minutes. This research suggests these longer signals occur when the collision results in the formation of a magnetar—a highly magnetic, rapidly spinning neutron star.
The Detection of Event EP250704a/GRB 250704B
On July 4, 2025, a collaborative effort involving the Einstein Probe, SVOM, and Insight-HXMT satellites captured a unique cosmic event designated EP250704a/GRB 250704B. While the associated gamma-ray burst lasted only half a second, the Einstein Probe recorded bright X-ray emissions that persisted for approximately ten minutes. This duration distinguishes the event from typical short-lived gamma-ray bursts. According to Eleonora Troja of the University of Rome Tor Vergata, the magnetar’s intense magnetic field damps power into the surrounding environment, causing the explosion to appear both brighter and longer-lasting.
Measuring Distance and Ruling Out Supernovae
To confirm the nature of the event, researchers used the VLT’s X-Shooter instrument to analyze the light from the source. By identifying specific absorption patterns, the team determined a redshift of z=0.6610, indicating the light traveled for more than six billion years to reach Earth. To verify the source was a neutron star merger rather than a massive star collapse, the team utilized the VLT’s FORS2 instrument to search for a supernova. The absence of a supernova, combined with the measured distance and the burst’s specific properties, provided the researchers with evidence that the event originated from a neutron star merger.
Future Implications for Gravitational Wave Astronomy
The ability to identify these X-ray flashes opens a new pathway for understanding the frequency of magnetar formation in the universe. Astronomers, including Niccolò Passaleva of the University of Rome Tor Vergata, anticipate that finding additional events will clarify how often these mergers result in magnetars. The next phase of research aims to correlate these X-ray flashes with simultaneous detections of gravitational waves, providing a more comprehensive view of the dynamics involved in neutron star collisions. This work was supported by a European Research Council (ERC) Consolidator grant and conducted as part of the “QUEENB: a QUEst for Elusive Neutron star and Black hole mergers” program.
Frequently Asked Questions About X-Ray Transients
What is the difference between this event and a standard gamma-ray burst?
Standard gamma-ray bursts from neutron star mergers typically last less than two seconds. This specific event, however, produced X-ray emissions that remained visible for nearly ten minutes.
Why did researchers look for a supernova?
A supernova is a common indicator of a massive star’s death. Its absence helped the research team confirm that the X-ray flash was the result of a neutron star merger rather than a collapsing star.
How far away did this explosion occur?
The event occurred more than six billion years ago, based on a measured redshift of z=0.6610.
What is a magnetar?
A magnetar is a type of neutron star that possesses an extremely powerful magnetic field and spins rapidly. When these objects form after a merger, they can release energy that keeps an explosion visible for a longer duration.
Worth a look