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Description
The total cosmic ray electron spectrum (electrons plus positrons) exhibits a break at a particle
energy of ∼ 1 TeV and extends without any attenuation up to ∼ 20 TeV. Synchrotron and inverse
Compton energy losses strongly constrain both the age and the distance of the potential sources of
TeV and multi-TeV electrons to ≈ $10^5$ yr and ≈ 100 − 500 pc, depending on both the absolute value
and energy dependence of the cosmic ray diffusion coefficient. This suggests that only a few, or just
one nearby discrete source may explain the observed spectrum of high energy electrons. On the
other hand the measured positron fraction, after initially increasing with particle energy, saturates
at a level well below 0.5 and likely drops above ∼ 400−500 GeV. This means that the local source(s)
of TeV electrons should not produce positrons in equal amount, ruling out scenarios involving
pulsars/pulsar winds as the main sources of high energy leptons. In this paper we show that a
single, local, and fading source can naturally account for the entire spectrum of cosmic ray electrons
in the TeV domain. Even though the nature of such source remains unclear, we discuss known
cosmic ray accelerators, such as supernova remnant and stellar wind shocks, which are believed to
accelerate preferentially electrons rather than positrons.
Keywords
cosmic rays
| Subcategory | Theoretical Results |
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