Astronomers Observe Unprecedented Repeating Gamma-Ray Burst

Astronomers have identified a gamma-ray burst (GRB) that defies conventional understanding by exhibiting multiple explosions over a 24-hour period. Designated GRB 250702B, this event was first detected on July 2, 2025, by NASA's Fermi Gamma-ray Space Telescope, which observed three bursts from the same location within a few hours. Subsequent analysis revealed that the Einstein Probe had detected X-ray activity from the same source a day earlier.

Traditionally, GRBs are singular, catastrophic events resulting from the collapse of massive stars or the merger of neutron stars, typically lasting from milliseconds to minutes. The repeated and prolonged nature of GRB 250702B challenges these models. Antonio Martin-Carrillo, co-lead researcher from University College Dublin, stated, "This event is unlike any other seen in 50 years of GRB observations."

To pinpoint the source, astronomers utilized the Very Large Telescope (VLT) equipped with the HAWK-I infrared camera. Observations confirmed that GRB 250702B originated from a galaxy beyond the Milky Way, a finding later corroborated by the Hubble Space Telescope. The host galaxy's characteristics suggest it is located billions of light-years away.

The unique properties of GRB 250702B have led researchers to consider alternative explanations. One hypothesis involves the tidal disruption of a white dwarf by an intermediate-mass black hole, a scenario that could account for the observed periodicity and duration. However, further observations are necessary to confirm this theory. Andrew Levan, co-lead researcher from Radboud University, remarked, "If this is a massive star, it is a collapse unlike anything we have ever witnessed before."

The research team continues to monitor the aftermath of GRB 250702B using advanced instruments, including the James Webb Space Telescope, aiming to gain deeper insights into this unprecedented cosmic event.