Possible Matter-Antimatter Annihilation in Space Explosion Detected

A research team investigating the brightest gamma-ray burst recorded in at least 10,000 years has identified a unique emission line that could provide valuable insights into the extreme physics occurring within the blast. This finding was published in Science and revolves around an emission line detected approximately 280 seconds after the beginning of the gamma-ray burst. 
 
Maria Edvige Ravasio, the lead author of this study from Radboud University in the Netherlands, described her excitement upon first seeing this signal. She stated that their analysis revealed it to be "the first high-confidence emission line ever seen in 50 years of studying GRBs." 
 
The gamma-ray burst under investigation is believed to have been triggered by a massive space explosion caused by a star's spectacular death throes. Identified as GRB 221009A or 'BOAT' (Brightest of All Time), it’s not literally considered as such but certainly ranks as one of the most luminous events recorded thus far. 
 
This extraordinary event offers researchers insight into stellar collapse processes due to its intense X- and gamma-rays, which momentarily overwhelmed many space-based observatories. Yet almost two years after the event, scientists are still uncovering new details about BOAT. 
 
Om Sharan Salafia from INAF-Brera Observatory and co-author on this paper emphasized how different BOAT is compared with other similar phenomena previously studied: "We've determined that the odds this feature is just a noise fluctuation are less than one chance in half a billion." 
 
First observed by NOIRLab's Gemini South telescope funded by the National Science Foundation in October 2022, BOAT took place approximately 2.4 billion light-years away. The sheer magnitude of its brilliance quickly overwhelmed X- and gamma-ray telescopes deployed across various locations in outer space. 
 
Later confirmed as BOAT during March 2023, although not technically being 'the brightest', it was recognized as probably “the brightest burst at X-ray and gamma-ray energies to occur since human civilization began,” as described by an astrophysicist. The BOAT event was characterized as a once-in-10,000-year occurrence, and its X-ray observations were published in The Astrophysical Journal Letters. 
 
In June of the same year, another research group analyzed the structure of BOAT's gamma-ray jet, which could potentially serve as a template for understanding other energy bursts originating from collapsing stars. 
 
A more comprehensive analysis of BOAT's gamma-ray energy output was published later that year, in November. This study concluded that the star responsible for creating BOAT was 20 times heavier than our sun, with a burn duration lasting hundreds of seconds. Over 140 gamma-rays exceeding 3 teraelectronvolts were identified during this event, which challenged current models explaining GRB afterglows. 
 
The emission line observed by researchers lasted around 40 seconds, reaching peak energies nearly equal to twelve million electronvolts. They believe this resulted from collisions between electrons and their antimatter counterparts, known as positrons. 
 
Gor Oganesyan, co-author on this paper and researcher at Gran Sasso Science Institute, explained: "When an electron and a positron collide, they annihilate." He further added: "Because we're looking into the jet, where matter is moving at near-light speed, this emission becomes greatly blueshifted and pushed toward much higher energies." 
 
This implies that these electron-positron pairs must have been moving towards us almost at light speed (99.9%) for achieving such high-energy peaks seen by researchers while studying BOAT explosion dynamics. 
 
Despite being two years since its occurrence, scientists are still investigating the aftermaths left behind by this extraordinary explosion. Just recently, in April, another team utilizing the Webb Space Telescope discovered evidence suggesting it originated from supernova activity, marking the end phase of stellar evolution through massive explosions causing star deaths but leaving no trace evidence concerning heavy elements produced during these events, thus keeping their universal origins a mystery. 
 
Continued exploration of BOAT's aftermath and future observations of other gamma-ray sources could potentially provide more answers to these intense cosmic events.