Astronomers Discover Gamma Ray Burst with Energy Up to 18 Teraelectronvolts Near Earth on October 9.
The newly discovered gamma ray burst, named GRB221009A, is the strongest ever observed, releasing 18 teraelectronvolts of energy. Scientists are still analyzing the measurement results, but if the discovery is confirmed, this will be the first gamma ray burst with energy exceeding 10 teraelectronvolts. GRB221009A originates from the direction of the constellation Sagitta and can be observed through telescopes for over 10 hours, making it one of the longest gamma ray bursts ever recorded.
The strongest gamma ray burst in the universe. (Photo: NASA/ESA)
Gamma ray bursts were discovered accidentally by U.S. military satellites in the 1960s, likely produced when a massive star explodes at the end of its life before collapsing into a black hole, or when a super-dense stellar remnant known as a neutron star collides. Within seconds, these explosions release energy equivalent to that produced by the Sun over its 10 billion-year lifespan.
Initially, the intensity of the gamma ray burst puzzled astronomers. They believed it must have originated from a relatively nearby source. At first, they also thought the energy was arriving in the form of X-rays rather than gamma rays. Subsequent analysis of the signals confirmed that the gamma ray burst came from a source 2.4 billion light-years away. Although not too close, this gamma ray burst is still the nearest ever observed.
While it is at a safe distance from Earth, a gamma ray burst could cause disaster if it were closer. Within a few thousand light-years from Earth, such a gamma ray burst could strip away the protective ozone layer and cause mass extinction. Researchers believe that one of the largest extinction events in Earth’s history during the Ordovician period, which occurred around 450 million years ago, may have been caused by a gamma ray burst, according to NASA.
Despite GRB221009A being over 20 times closer to Earth than typical gamma ray bursts, it does not raise concerns among astronomers. “This event is very close and has high energy, which means the radio, optical, X-ray, and gamma ray light it produces is extremely bright and easy to observe. Therefore, we can study this gamma ray burst with many large and small telescopes around the world, collecting a comprehensive dataset as it brightens and then fades away,” said Gemma Anderson, an astronomer at Curtin University in Australia.
According to researchers, GRB221009A appears to be a long gamma ray burst, but the exact cause of its formation remains unclear. Many ground-based and Earth-orbiting telescopes are currently focusing on the galaxy where the gamma ray burst occurred. These instruments will attempt to observe the light produced by the explosion across multiple wavelengths to determine its origin. Initial observational results were published on October 9 in the Astronomer’s Telegram.
