Astronomers Observe Unprecedented Day-Long, Repeating Gamma-Ray Burst
A gamma-ray burst lasting approximately 24 hours and exhibiting repeated emissions challenges existing astrophysical models.
On July 2, 2025, astronomers detected a gamma-ray burst (GRB) designated GRB 250702B, notable for its unprecedented duration of about 24 hours and multiple emissions over that period. This contrasts sharply with typical GRBs, which usually last from milliseconds to a few minutes.
The initial detection was made by NASA's Fermi Gamma-ray Space Telescope, which recorded three distinct bursts from the same source within several hours. Subsequent data from the Einstein Probe indicated that the source had been active nearly a day earlier. Further observations using the Very Large Telescope (VLT) and the Hubble Space Telescope confirmed that the burst originated from a distant galaxy, suggesting a highly energetic event.
The unique characteristics of GRB 250702B do not align with existing models of GRB origins, such as the collapse of massive stars or the merger of neutron stars. One hypothesis proposes that the event resulted from a white dwarf being disrupted by an intermediate-mass black hole, a scenario that remains to be confirmed. Researchers continue to analyze data from instruments like the VLT's X-shooter spectrograph and the James Webb Space Telescope to better understand this anomalous event.