Unprecedented Seven-Hour Gamma-Ray Burst GRB 250702B Captivates Astrophysicists

On July 2, 2025, a remarkable cosmic event was detected, cataloged as gamma-ray burst GRB 250702B, which lasted over seven hours, setting a new record for gamma-ray burst duration. This unprecedented event was first observed by the Gamma-ray Burst Monitor aboard NASA’s Fermi Space Telescope, which identified three distinct high-energy flashes from a single celestial region. The event's total duration of approximately 25,000 seconds far exceeds the previous record of roughly 15,000 seconds, prompting a global response from astrophysicists and space agencies, including NASA and the European Space Agency (ESA).

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in YearsA gamma-ray burst raged on for seven hours. A researcher, who was behind its discovery, explains how.

The characteristics of GRB 250702B challenge existing classifications of gamma-ray bursts, which typically categorize them into short-duration (under 2 seconds) and long-duration (2 to 300 seconds) events. Eliza Neights, a researcher at NASA’s Goddard Space Flight Center, proposed a new theoretical model involving a helium star merger. This scenario suggests that a stellar-mass black hole orbits a helium-rich star, consuming it as the star expands. This interaction could produce a long-lived relativistic jet, resulting in the observed gamma-ray emissions.

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in YearsA gamma-ray burst raged on for seven hours. A researcher, who was behind its discovery, explains how.

The exceptional nature of GRB 250702B has highlighted limitations in current gamma-ray observatories, which are primarily designed to detect brief, high-intensity bursts. Many longer-duration events may go unnoticed due to their lower luminosity and gradual energy release. In response, NASA has begun integrating criteria for long-duration bursts into the mission planning for the upcoming Compton Spectrometer and Imager (COSI), set to launch in 2027. This new instrument will operate in the MeV gamma-ray range, enhancing sensitivity to low-intensity emissions.

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in Years

Eliza Neights emphasized the importance of adapting detection methods, stating, “We detect these jets as gamma-ray bursts when they happen to point towards us.” She noted that the prolonged nature of GRB 250702B ruled out conventional models, reinforcing the need for updated detection algorithms. The research team is also conducting a retrospective search of archival datasets to identify previously overlooked long-duration bursts.

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in Years

Some astrophysicists have expressed skepticism regarding the helium merger model, arguing that more data is needed to confirm this hypothesis. The absence of direct redshift measurements and the unidentified host galaxy complicate the interpretation of GRB 250702B, leaving room for alternative explanations.

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in Years

As researchers continue to analyze data from GRB 250702B, the findings will inform future observational strategies and enhance understanding of gamma-ray bursts. The upcoming launch of COSI aims to improve detection capabilities, potentially uncovering more long-duration bursts that have eluded current monitoring systems.

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in Years

“Primarily, we use widefield, high-energy monitoring, typically with space telescopes that see a very large part of the sky at a time,” — Eliza Neights, NASA Goddard Space Flight Center

A gamma-ray burst raged on for seven hours. A researcher, who was behind its discovery, explains how.

“When they expand, the orbiting black hole will end up inside the stellar envelope and consume the star rapidly.” — Eliza Neights, NASA Goddard Space Flight Center

A gamma-ray burst raged on for seven hours. A researcher, who was behind its discovery, explains how.

“The 2025 event is now being used as a reference scenario for algorithm testing and detection model updates.” — NASA Research Team

Astronomers Detected a Powerful Space Signal Pulsing Toward Earth for Seven Hours, Unlike Anything Seen in Years