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As I've discussed, unexplained signals in a variety of data sets point to four hints of possible dark matter detection. First, the DAMA [66] annual modulation [51] signal could be compatible with a ∼10 GeV WIMP. However, since other experiments do not see any signal at all, the DAMA results must be checked. Currently three different experiments are planning to repeat the DAMA setup with NaI crystals: SABRE, COSINE, and ANAIS.

Second, the Fermi-LAT γ-ray excess from the direction of the Galactic Center could be due to WIMP annihilation. However, point sources (such as pulsars) constitute another explanation of the excess that is at least as good or better.

Third, the possible 3.5 keV X-ray line from clusters and from M31 could be explained by a 7 keV sterile neutrino, but this interpretation is very controversial.

A fourth intriguing signal, not yet mentioned in this article, is the 511 keV γ-ray line in INTEGRAL data. [131, 132] This is seen in the Galactic Bulge out to 6 degrees (3 kpc). There is no clear astrophysical explanation. Low mass X-ray binaries were thought to be a compelling explanation which is now being ruled out. The explanation for the line could be dark matter annihilation to e+e pairs. This would be MeV dark matter. [133]

The future holds interesting studies of these signals as well as the continuing hunt for dark matter.

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