The cosmic electron spectrum is like fingerprints at a crime scene. Particles arriving from the depths of the Galaxy carry in their energies the traces of those that produced them. For a long time, the picture was blurred: instruments with wide energy bins, like out-of-focus photographs, did not reveal details. But recently, scientists got a sharp image — a high-precision spectrum measured by the ATIC instrument with a resolution of about 3%. And unexpected lines appeared on it.

Previously, it was believed that all positrons in cosmic rays are born as secondaries: protons colliding with interstellar gas produce electron-positron pairs. But data from PAMELA and Fermi/LAT showed that the positron fraction increases with energy, which the secondary model cannot explain. Two main suspects emerged: annihilation of dark matter particles and nearby pulsars — rapidly rotating neutron stars that, like lighthouses, emit streams of particles. Both scenarios described the low-energy data equally well, and they could not be distinguished.

The new ATIC spectrum changed the game. In the 200–600 GeV range, it showed not a smooth curve but a distinct jagged structure: three peaks around 250, 350, and 450 GeV, and three dips between them. The statistical significance is 99.7%, and the structure was reproduced in two independent flights. These are not random fluctuations but real fingerprints.

Fitting the fine structure with several pulsars is possible with reasonable parameters. Moreover, in this case, the positron fraction should rise rapidly with energy, reaching about 0.4 at 400–500 GeV, which is consistent with Fermi/LAT data up to 200 GeV. Thus, the fingerprints begin to form a portrait of specific sources.

Now that we have a sharp image, it remains to confirm it with independent experiments. If the fine structure is reproduced on other instruments, it will become a decisive argument in favor of the pulsar origin of the anomalies. And then the mystery of the positron excess will be solved — not by dark matter, but by familiar cosmic lighthouses.