<i>L_α</i> Line of Dark Positronium as a Nongravitational Detection of DM

Abstract

An attempt to predict the new atomic dark matter lines is done on the example of a dark lepton atom-positronium. Its Layman-alpha line with the energy near 3 GeV may be observable if the appropriate conditions are realized. For this we have studied a γ -ray excess in the center of our galaxy. In principle, this excess may be produced by the L α line of a dark positronium in the medium with Compton scattering. The possibility of observations of an annihilation line (E~300 TeV) of dark positronium is also predicted. Other proposals to observe the atomic dark matter are shortly described. Besides, H α line (1.3 μ ) of usual positronum must be observable in the direction on the center of our galaxy.