Astronomers have identified a record-breaking X-ray burst lasting nearly ten minutes, which they attribute to the collision of two neutron stars six billion years ago.
X-ray emissions lasted ten minutes after gamma burst
The event began with a gamma-ray burst lasting approximately half a second. While typical gamma-ray bursts from neutron star mergers vanish in under two seconds, the X-ray radiation from this specific event persisted for nearly ten minutes. Niccolò Passaleva, a doctoral student who coordinated the follow-up observations, stated this is the longest immediate X-ray burst ever observed during a neutron star merger.
Passaleva initiated the observation process from a laptop while traveling by train after receiving an alert about the flash. To capture the fading light, the team used the Very Large Telescope (VLT) in Chile, as the speed of data acquisition was critical to analyzing the event’s origins.
Light traveled six billion years to Earth
Analysis conducted with the X-Shooter instrument on the VLT revealed that the light from the collision traveled for more than six billion years before reaching Earth. This timeline places the event long before the formation of the Sun and Earth.
Researchers specifically looked for a supernova, which would have indicated the death of a single massive star. Because no supernova was detected and the burst characteristics matched specific patterns, the team concluded the event was a collision between two neutron stars.
Magnetar formation explains prolonged radiation
The unusual duration of the X-ray burst led researchers to hypothesize the creation of a magnetar. Astronomer Eleonora Troja explained that if a magnetar—a neutron star with an exceptionally strong magnetic field—is the remnant of the collision, it can continue to radiate energy for a longer period.
This finding provides a potential explanation for hundreds of mysterious bursts detected by the Einstein Probe satellite since 2024. Passaleva noted that identifying more of these X-ray bursts will help scientists determine how frequently magnetars are produced during neutron star mergers.
Neutron Star Mergers vs. Supernovae
| Feature | Neutron Star Merger (This Event) | Supernova (Massive Star Death) |
|---|---|---|
| Gamma-ray Duration | Short (approx. 0.5 seconds) | Variable |
| X-ray Duration | Extended (up to 10 minutes) | Different decay pattern |
| Visual Evidence | No supernova detected | Visible supernova explosion |
| Possible Remnant | Magnetar | Black hole or neutron star |
Neutron Star Collision Questions
What is a magnetar and why does it matter here?
A magnetar is a type of neutron star with a magnetic field significantly stronger than a standard neutron star. In this event, the magnetar’s energy is believed to have powered the X-ray emissions for ten minutes, far exceeding the half-second gamma burst.
How did scientists rule out a supernova?
The team used the X-Shooter instrument on the Very Large Telescope to scan for the light signature of a dying massive star. The total absence of a supernova, combined with the short gamma-ray burst, pointed directly to a binary neutron star collision.
What is the Einstein Probe’s role in this research?
The Einstein Probe satellite has recorded hundreds of X-ray flashes since 2024, many of which have unknown origins. This study suggests that a portion of those unidentified flashes may be caused by neutron star mergers creating magnetars.
Astronomers are now working to capture a similar event using gravitational wave detectors simultaneously with light observations to confirm the physical processes occurring during these mergers.
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