Gamma ray emissions may hint at elusive dark matter

A new research of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter - an unknown substance making up most of the material universe.

Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study, said that the signal they find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models.

When astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains. This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) -- roughly a billion times greater than that of visible light-and extends outward at least 5,000 light-years from the galactic center.

Hooper and his colleagues conclude that annihilations of dark matter particles with a mass between 31 and 40 GeV provide a remarkable fit for the excess based on its gamma-ray spectrum,its symmetry around the galactic center, and its overall brightness.

The study has been submitted to the journal Physical Review D for publication.