Record X-ray flash may reveal magnetar birth in neutron star merger

The Einstein Probe satellite detected EP250704a/GRB 250704B, a nearly 10-minute X-ray flash — the longest ever seen from a neutron star merger. VLT observations measured a redshift of z=0.6610 and found no supernova, pointing to the birth of a magnetar.

• Gamma-ray burst lasted about 0.5 seconds, X-ray emission nearly 10 minutes
• Redshift of z=0.6610 means light traveled over 6 billion years to Earth
• No supernova found, supporting a neutron star merger origin
• Event was detected on July 4, 2025 by SVOM, Insight-HXMT and Einstein Probe