Astronomers Detect Unprecedented Repeating Gamma-Ray Burst
Astronomers have observed a gamma-ray burst, GRB 250702B, that repeated multiple times over a 24-hour period, challenging existing models of such cosmic events.
On July 2, 2025, astronomers detected a gamma-ray burst (GRB) designated GRB 250702B, which exhibited an unprecedented pattern by repeating multiple times over a 24-hour period. This behavior challenges the conventional understanding of GRBs, which are typically singular, short-lived events resulting from catastrophic cosmic occurrences.
The initial detection was made by NASA's Fermi Gamma-ray Space Telescope, which recorded three distinct bursts from the same source within a few hours. Subsequent analysis revealed that the Chinese Academy of Sciences' Einstein Probe had observed related X-ray activity nearly a day earlier. This extended and repeating nature of GRB 250702B is unlike any previously recorded GRB.
To pinpoint the origin of this anomaly, astronomers utilized the European Southern Observatory's Very Large Telescope (VLT) equipped with the HAWK-I infrared camera. These observations, later confirmed by the NASA/ESA Hubble Space Telescope, determined that the source resides in a distant galaxy, potentially billions of light-years away. The extragalactic location implies that the burst was extraordinarily powerful.
The exact cause of GRB 250702B remains uncertain. Traditional explanations, such as the collapse of a massive star or a tidal disruption event where a star is torn apart by a black hole, do not fully account for the observed characteristics. One hypothesis suggests that the event could involve a white dwarf being destroyed by an intermediate-mass black hole, a scenario that has not been previously observed.
Researchers are continuing to monitor the aftermath of GRB 250702B using various instruments, including the VLT's X-shooter spectrograph and the James Webb Space Telescope, to gain further insights into this unique and enigmatic cosmic event.