Novel cosmic-ray electron and positron constraints on MeV dark matter particles

Understand

MeV dark matter (DM) particles annihilating or decaying to electron-positron pairs cannot, in principle, be observed via local cosmic-ray (CR) measurements because of the shielding solar magnetic field.

• In this letter, we take advantage of spacecraft Voyager 1's capacity for detecting interstellar CRs since it crossed the heliopause in 2012.
• This opens up a new avenue to probe DM in the sub-GeV energy/mass range that we exploit here for the first time.
• From a complete description of the transport of electrons and positrons at low energy, we derive predictions for both the secondary astrophysical background and the pair production mechanisms relevant to DM annihilation or decay down to the MeV mass range.