The X-Ray Line Feature At 3.5 Kev In Galaxy Cluster Spectra

Understand

Recent work by Bulbul et al.

• and Boyarsky et al.
• has suggested that a line feature at approx.
• 3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate.