Galactic Center GeV excess
The Galactic Center GeV Excess (GCE) is an unexpected surplus of gamma-ray radiation in the center of the Milky Way Galaxy. 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.
See also
- Galactic Center – Rotational center of the Milky Way galaxy
- Gamma-ray astronomy – Observational astronomy performed with gamma rays
- List of unsolved problems in astronomy
References
Further reading
- Ackermann, M.; et al. (May 2017). "The Fermi Galactic Center GeV Excess and Implications for Dark Matter". The Astrophysical Journal. 840 (1). 43. arXiv:1704.03910. Bibcode:2017ApJ...840...43A. doi:10.3847/1538-4357/aa6cab. S2CID 119481146.
- Shang, Liangliang; et al. (May 2018). "Interpretations of galactic center gamma-ray excess confronting the PandaX-II constraints on dark matter-neutron spin-dependent scatterings in the NMSSM". European Physical Journal C. 78 (5). 390. arXiv:1804.08797. Bibcode:2018EPJC...78..390S. doi:10.1140/epjc/s10052-018-5827-8. S2CID 55864561.