Gamma-ray radiation (greater than 1 Gev) detected over the entire sky; brighter areas are more radiation (five year study by theFermi Gamma-ray Space Telescope: 2009–2013)
TheGalactic Center GeV Excess (GCE) is an unexpected surplus ofgamma-ray radiation in the center of theMilky Way Galaxy. This spherical source of radiation was first detected in 2009[1][2] by theFermi Gamma-ray Space Telescope and is unexplained by direct observation.[3] 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.[4][5][6][7]
Some astronomers argue that self-annihilatingdark matter (which is not otherwise known to radiate) may be the cause of the GCE, while others prefer a population ofpulsars (which have not been observed) as the source.[8][3]
Astronomers have suggested that self-annihilating dark matter may be a dominant contributor to the GCE, based on analysis usingnon-Poissonian template fitting statistical methods,[5]wavelet methods,[7] and studies by other astronomers may support this idea.[9][10] More recently, in August 2020, other astronomers have reported that self-annihilating dark matter may not be the explanation for the GCE after all.[11][12] Other hypotheses include ties to a yet unseen population of millisecond pulsars[13][14] or young pulsars, burst events, the stellar population of thegalactic bulge,[15] or the Milky Way's centralsupermassive black hole.[16]
^Goodenough, Lisa; Hooper, Dan (11 November 2009). "Possible Evidence For Dark Matter Annihilation In The Inner Milky Way From The Fermi Gamma Ray Space Telescope".arXiv:0910.2998 [hep-ph].
