A local fading accelerator and the origin of TeV cosmic ray electrons

International audienceThe cosmic ray electron spectrum exhibits a break at a energy of ∼ 1 TeV and extends without anyattenuation up to ∼ 20 TeV. Energy losses strongly constrain the time of emission of ∼ 20 TeVelectrons to ≈ 2 × 104 yr and the distance of the potential source(s) to ≈ 100 − 500 pc, dependingon the cosmic ray diffusion coefficient. This suggests that maybe a single nearby source maydominate the multi-TeV electron spectrum. Here we show that a local source of age ≈ 105 yr, thatcontinuously inject electrons with a fading luminosity (on timescales of ∼ 104 yr), can naturallyexplain the entire spectrum of cosmic ray electrons in the TeV domain. Despite a nearby pulsarmay easily explain the fading profile, the drop of the positron fraction above ∼ 400 − 500 GeV,make such scenario problematic. Supernova remnants accelerate mostly electrons, rather thanpositrons, but they can hardly provide a fading injection. A third class of potential are stellarwind shocks, which however are likely to have a constant luminosity on timescales >> 10 kyr andprobably cannot match the time requirement of our potential source. Therefore, the identificationof the potential source(s) of multi-TeV electrons probably requires a profound revision of thepresent paradigms of acceleration and escape in such objects