DNews reports that sterile neutrinos could be the candidates for dark matter. Those are neutrinos that have masses between the electron neutrino (0.3 eV) and muon neutrino (0.115 MeV). In fact, it seems that the sterile neutrino might have a mass of just about 3.55 keV as it gives off X rays in that band when it decays.
We still need to confirm this, but the researchers have found a small bump in the X ray band at about 3.55 keV that correlate with the results from gravitational predictions:
The hunt for the dark matter particle is decades old, but we hope it has come to a close. Watch below the history of this search and how they could detect the sterile neutrinos in the X ray band: