Galactic Center Gev Excess

This spherical source of radiation was first detected in 2009 by the Fermi Gamma-ray Space Telescope and is unexplained by direct observation. Two percent of the gamma ray radiation in a 30° radius circle around the galactic center is attributed to the GCE. As of 2020^[update], this excessive (and diffused) gamma-ray radiation is not well understood by astronomers.

Some astronomers argue that self-annihilating dark matter (which is not otherwise known to radiate) may be the cause of the GCE, while others prefer a population of pulsars (which have not been observed) as the source.

Astronomers have suggested that self-annihilating dark matter may be a dominant contributor to the GCE, based on analysis using non-Poissonian template fitting statistical methods, wavelet methods, and studies by other astronomers may support this idea. More recently, in August 2020, other astronomers have reported that self-annihilating dark matter may not be the explanation for the GCE after all. Other hypotheses include ties to a yet unseen population of millisecond pulsars or young pulsars, burst events, the stellar population of the galactic bulge, or the Milky Way's central supermassive black hole.

• Galactic Center – Rotational center of the Milky Way galaxy
• Gamma-ray astronomy – Observational astronomy performed with gamma rays
• List of unsolved problems in astronomy