The most powerful gamma-ray burst in history can shed light on new physics – axions and the mystery of dark matter

The more scientists study data from the gamma-ray burst GRB 221009A, which is literally called the “brightest of all time” or BOAT, the more interesting their findings become. New work by Italian astronomers, published as a follow-up to a report from March last year, links this event to string theory and the possible explanation of dark matter by axion particles or similar particles. If this hypothesis is confirmed, it will be a breakthrough in cosmology and new physics.

Jet as imagined by the artist. Image source: NASA Goddard Space Flight Center

The GRB 221009A flare, we recall, was recorded in October 2022. It blinded all gamma-ray telescopes except for one Chinese one, which was undergoing maintenance at the time and turned off almost all sensors. A more advantageous position was occupied by ground-based high-energy particle telescopes, which monitored the secondary flow of particles in the Earth’s atmosphere caused by the primary flow. One such telescope was China’s LHAASO (Large High Altitude Airstream Observatory). It was the analysis of LHAASO data that led Italian scientists to a possible discovery.

A team of researchers led by Professor Giorgio Galanti from Italy’s National Institute of Astrophysics (INAF) discovered discrepancies in the observational data. The observatory recorded gamma-ray photon energy up to 18 TeV (teraelectronvolt). According to the researchers, such energy cannot be explained within the framework of modern physics.

According to modern cosmological models, high-energy photons from the source GRB 221009A, located 2.4 billion light years from Earth, should have interacted with photons from diffuse extragalactic background radiation. This interaction should have reduced their energy to 10 TeV and below. However, observational evidence suggests otherwise, forcing scientists to consider alternative models to explain the phenomenon.

In particular, the high energy of photons recorded by the observatory indicates the greater transparency of the Universe, both within and between galaxies. This is possible within the framework of string theory when photons interact with axion-like particles (ALPs, axion-like particles), which the researchers substantiated in their work published on the arXiv website on December 30, 2024.

Axions or similar particles are considered candidates for the role of dark matter – an elusive substance that interacts with ordinary matter exclusively through gravitational interaction, which is extremely weak. According to calculations, about 85% of all matter in the Universe is represented by dark matter, the existence of which can only be determined indirectly. The detection of photons with extremely high energy can also serve as indirect confirmation of the existence of axions or their varieties of the ALPs family. However, this requires independent study and further research by other scientific groups.