Nearly a century after dark matter was first proposed, scientists may have captured the first direct evidence of the elusive substance. A new study suggests that gamma rays emanating from the centre of the Milky Way bear the signature of dark matter, potentially marking a turning point in the decades-long search for the mysterious material that is said to make up 27% of the cosmos.
Prof Tomonori Totani, an astrophysicist at the University of Tokyo, analysed data from Nasa's Fermi Gamma-ray Space Telescope and spotted a pattern of gamma rays that matched the shape of the dark matter halo spreading out from the galactic heart. "This could be a crucial breakthrough in unraveling the nature of dark matter," he said. The findings are published in the Journal of Cosmology and Astroparticle Physics.
Dark matter was first inferred in the 1930s when Swiss astronomer Fritz Zwicky noticed galaxies spinning faster than their mass allowed. Since then, scientists have postulated that it is made of weakly interacting massive particles (wimps) that can annihilate each other when they collide, releasing gamma rays. If Totani's observations are correct, the gamma rays would be emitted by particles 500 times heavier than a proton.
However, experts urge caution. Prof Justin Read of the University of Surrey noted that the lack of significant gamma ray signals from dwarf galaxies argues against Totani's interpretation. Prof Kinwah Wu of UCL added: "We need extraordinary evidence for an extraordinary claim. This analysis has not reached this status yet." Further work is required to rule out other astrophysical processes that could mimic the signal.
