Einstein Probe Captures Record 10-Minute X-Ray Flash from Neutron Star Merger

Key points

• The event EP250704a was detected on July 4, 2025, by the joint European-Chinese Einstein Probe.
• It consisted of a half-second gamma-ray burst followed by a 10-minute X-ray emission, the longest prompt X-ray flash ever observed from a neutron star merger.
• The light from the event traveled for approximately 6 billion years to reach Earth.
• Researchers ruled out a supernova as the cause, linking the burst to a compact object merger.
• The prolonged emission is attributed to the formation of a magnetar, a rapidly spinning neutron star with an intense magnetic field.
• The study was published in Science Bulletin on September 30, 2026.

Background

This discovery builds on previous findings regarding high-energy cosmic events, such as the identification of distant blazars and the detection of gravitational waves from neutron star mergers. It aligns with ongoing efforts to understand the remnants of stellar collisions and their role in multi-messenger astronomy.

How outlets are covering it

Space.com and The Economic Times emphasize the event's significance as a record-breaking X-ray flash, highlighting its potential to explain unexplained cosmic bursts. ScienceDaily focuses on the technical implications, noting that Einstein Probe's wide-field capabilities revealed a 'hidden phase' of neutron star mergers that traditional gamma-ray instruments missed. All sources agree on the magnetar hypothesis but differ in emphasis: Space.com and The Economic Times stress the forging of heavy elements like gold, while ScienceDaily highlights the event's value for constraining the neutron star equation-of-state and linking electromagnetic signals to gravitational waves.

Why it matters

This event provides a new observational window into the aftermath of neutron star mergers, potentially explaining hundreds of unexplained X-ray flashes detected by the Einstein Probe since 2024. It offers a new electromagnetic counterpart to gravitational-wave sources, enhancing multi-messenger astronomy and helping scientists understand the formation of magnetars and heavy elements in the universe.

What to watch

Astronomers will continue monitoring for similar X-ray flashes to determine how frequently neutron star mergers produce magnetars. Future studies may use these events to further constrain the neutron star equation-of-state and improve the detection of gravitational-wave counterparts.