Astronomers Observe Unprecedented 7-Hour Gamma-Ray Burst

On July 2, 2025, astronomers detected an unprecedented gamma-ray burst (GRB), designated GRB 250702B, which lasted over seven hours—far exceeding the typical duration of such events. This extraordinary phenomenon challenges existing astrophysical models and suggests potential new mechanisms for cosmic explosions.

Gamma-ray bursts are the universe's most energetic explosions, typically lasting from milliseconds to a few minutes. They are usually associated with the collapse of massive stars or the merger of neutron stars, leading to the formation of black holes. The detection of GRB 250702B, with its prolonged emission, places it in a unique category, prompting a reevaluation of existing classification systems.

The initial detection was made by NASA's Fermi Gamma-ray Space Telescope, which observed three distinct bursts from the same source over several hours. This was followed by observations from the European Space Agency's Integral satellite and China's Einstein Probe, which detected associated X-ray transients. Ground-based telescopes, including the Very Large Telescope (VLT) equipped with the HAWK-I infrared camera, and the Hubble Space Telescope, pinpointed the event's location in a distant galaxy approximately 8 billion light-years away in the constellation Scutum.

The prolonged duration and repeating nature of GRB 250702B challenge current astrophysical models. Traditional GRBs are classified into short-duration (less than 2 seconds) and long-duration (more than 2 seconds) categories. The seven-hour duration of GRB 250702B, coupled with its repeating bursts, suggests the existence of previously unknown processes or conditions leading to such prolonged emissions. Several hypotheses have been proposed, including the collapse of a massive star, a star being torn apart by a black hole, or the merger of a helium star with a black hole. However, none can fully account for all the observed properties of this explosion.

A study published on December 11, 2025, by the Gran Sasso Science Institute provides new insights into this phenomenon. The researchers suggest that the exceptional duration and repeating nature of GRB 250702B may be due to a previously unknown mechanism in cosmic explosions. Professor Gor Oganesyan of the Gran Sasso Science Institute stated, "The Fermi telescope generally detects about four gamma-ray bursts every week. The exceptional duration of this event immediately drew the attention of scientists worldwide."

While gamma-ray bursts occur at cosmological distances and pose no direct threat to Earth, studying such events enhances our understanding of the universe's fundamental processes. Breakthroughs in astrophysics can inspire technological advancements and foster a greater appreciation for science among the public.

The detection and analysis of GRB 250702B represent a significant milestone in astrophysics, prompting a reevaluation of existing models and inspiring further research into the mechanisms behind gamma-ray bursts. This event underscores the importance of continuous observation and study of the cosmos to uncover its many mysteries.