Unusual activity at the centre of the Milky Way has raised new questions about dark matter, potentially pointing to a previously overlooked candidate. Researchers suggest that a lightweight, self-annihilating form of dark matter could be influencing cosmic chemistry in ways that have gone unnoticed. This theory proposes that when two of these dark matter particles collide, they annihilate each other, producing electrons and positrons. The presence of these particles in dense gas regions may explain why the Central Molecular Zone (CMZ) contains a significant amount of ionised gas. Scientists argue that this ionisation effect could be an indirect way of detecting dark matter, shifting the focus beyond its gravitational influence.
New Dark Matter Hypothesis
According to a study published in Physical Review Letters, a research team led by Shyam Balaji, Postdoctoral Research Fellow at King’s College London, suggests that dark matter with a mass lower than a proton may be responsible for the high levels of ionisation observed in the CMZ. Speaking to Space.com, Balaji explained that unlike traditional dark matter candidates, which are mainly studied through gravitational interactions, this form of dark matter might be detectable through its impact on the interstellar medium.
Dark Matter and Ionisation
Dark matter is believed to make up 85 percent of the universe’s mass, yet it remains undetectable by conventional methods due to its lack of interaction with light. The research indicates that even if dark matter annihilation is rare, it would be more frequent in galaxy centres where dark matter is expected to be denser. The team suggests that the ionisation observed in the CMZ is too strong to be explained by cosmic rays alone, making dark matter a compelling alternative explanation.
Future Observations and Implications
Balaji highlighted that existing observations do not contradict this hypothesis, and upcoming space missions, including
COSI gamma-ray telescope set to launch in 2027, could provide further evidence. If confirmed, this would open a new avenue for studying dark matter, not just through its gravitational effects but also through its chemical interactions within the galaxy.
