A massive matter/antimatter annihilation detected in space

While studying data from NASA's Fermi Gamma-ray Space Telescope, researchers observed a unique energy peak following the most luminous gamma-ray burst ever seen, suggesting the annihilation of electrons and positrons.


In October 2022, astronomers were taken by surprise by a gamma-ray burst (GRB) called BOAT (brightest-of-all-time). A team of scientists discovered that the Fermi telescope had detected an unprecedented spectral feature. Maria Edvige Ravasio from Radboud University and the Brera Observatory emphasizes the significance of this discovery, the first in 50 years of GRB studies.

Interactions between matter and light can reveal valuable information. At high energies, they demonstrate specific processes, such as the annihilation of particles and antiparticles producing gamma rays. Om Sharan Salafia, co-author of the study, believes the likelihood of this feature being a statistical fluctuation is very low.

GRBs are the most powerful explosions in the universe, emitting large quantities of gamma rays. They occur when the core of a massive star collapses into a black hole, generating jets of particles traveling almost at the speed of light. The BOAT, identified as GRB 221009A, is likely the brightest explosion in the last 10,000 years.

Five minutes after detecting the BOAT, an emission line appeared, peaking at 12 MeV. The team believes it results from the annihilation of electrons and positrons. Gor Oganesyan of the Gran Sasso Science Institute explains that this emission, observed in the jet, is significantly blueshifted.


If this interpretation is correct, the annihilated particles must have been traveling at approximately 99.9% of the speed of light. Elizabeth Hays, project scientist for Fermi, highlights that this discovery is a key to exploring this extreme environment further. The Fermi telescope is the product of an international collaboration, including significant contributions from France, Germany, Italy, Japan, Sweden, and the United States.

Matter/antimatter annihilation

Matter/antimatter annihilation is a physical phenomenon where a particle of matter meets its corresponding antiparticle. During this encounter, both particles mutually destroy or annihilate each other, releasing a large amount of energy in the form of gamma rays.

For example, when an electron meets a positron (its antiparticle), they annihilate to produce two gamma photons. This process is particularly important in astrophysics and particle physics as it helps to better understand fundamental interactions in the universe, particle properties, and extreme energetic phenomena such as gamma-ray bursts.