Astronomers Observe Unprecedented Long-Lasting and Repeating Gamma-Ray Burst
On July 2, 2025, NASA's Fermi Gamma-ray Space Telescope detected GRB 250702B, a gamma-ray burst lasting nearly 24 hours and exhibiting repeated emissions, challenging existing astrophysical models.
On July 2, 2025, NASA's Fermi Gamma-ray Space Telescope detected an extraordinary gamma-ray burst (GRB), designated GRB 250702B, which lasted nearly 24 hours and exhibited repeated emissions. This duration is significantly longer than typical GRBs, which usually last from milliseconds to minutes.
GRB 250702B was first identified by Fermi's Gamma-ray Burst Monitor, which recorded three distinct bursts from the same source over a few hours. Subsequent data from the Einstein Probe's Wide-field X-ray Telescope indicated that the activity had commenced almost a day earlier.
Initial observations suggested the burst originated within the Milky Way. However, follow-up studies using the Very Large Telescope's HAWK-I infrared camera and the Hubble Space Telescope confirmed that the explosion occurred in a distant galaxy, more than five billion light-years away.
The host galaxy of GRB 250702B is notably large and dusty, differing from the smaller, younger star-forming galaxies where GRBs are typically observed. This unusual environment may have played a role in the unique characteristics of the burst.
Scientists are considering several explanations for this unprecedented event. One hypothesis involves a massive star undergoing a unique collapse, resulting in an exceptionally energetic jet. Another possibility is a tidal disruption event, where a star is torn apart by an intermediate-mass black hole.
Further observations and analyses are ongoing to determine the exact cause of GRB 250702B and to understand its implications for astrophysical models.