Astronomers Detect Unprecedented Repeating Gamma-Ray Burst from Distant Galaxy

Astronomers have observed a gamma-ray burst (GRB) that defies conventional understanding by repeating multiple times 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 recorded three distinct bursts within hours. Subsequent analysis revealed that the Einstein Probe had observed related X-ray activity nearly a day earlier.

"This event is unlike any other seen in 50 years of GRB observations," said Antonio Martin-Carrillo, an astronomer at University College Dublin and co-author of a study published in The Astrophysical Journal Letters.

Gamma-ray bursts are typically brief, singular events resulting from catastrophic cosmic occurrences, such as massive star collapses or black hole interactions. The prolonged and repeating nature of GRB 250702B challenges these established models. Initial assessments suggested the burst originated within the Milky Way. However, observations using the European Southern Observatory's Very Large Telescope and the Hubble Space Telescope confirmed its extragalactic origin, placing it billions of light-years away.

"What we found was considerably more exciting: the fact that this object is extragalactic means that it is considerably more powerful," Martin-Carrillo noted.

The exact cause of GRB 250702B remains uncertain. One hypothesis involves an atypical massive star collapse, while another considers a tidal disruption event where a star is consumed by a black hole. Both scenarios would represent unprecedented astrophysical phenomena.

"If this is a massive star, it is a collapse unlike anything we have ever witnessed before," said Andrew Levan, an astronomer at Radboud University and co-lead author of the study.

Ongoing observations aim to unravel the mechanisms behind this extraordinary event, potentially offering new insights into the most energetic processes in the universe.