Charge-dependent spectral softenings of primary cosmic rays below the knee

The DAMPE satellite observed a universal charge-dependent spectral softening in primary cosmic rays, and ruled out mass-dependent softening with greater than 99.99% confidence. This finding provides crucial constraints on models of cosmic ray acceleration and propagation in the Milky Way.

The results, based on five years of DAMPE observations, suggest that cosmic ray sources in our galaxy accelerate particles through electromagnetic processes rather than gravitational ones, pointing toward supernova remnants as the dominant acceleration sites.