Low energy cosmic rays emitted by the orion complex into the local medium

Abstract

The excess of γ-ray emission in the energy range 3 – 7 MeV discovered by COMPTEL in the direction of the Orion complex may imply that there is a powerful source of low energy cosmic rays in the local galactic medium. Several interpretations of the excess have been suggested. One of them assumes that the emission is identified with nuclear de-excitation lines of excited ¹⁶O and ¹⁴C. To provide the excess the energy deposit in these nuclei should be as large as ∼ 10³⁹ erg s⁻¹. If a comparable part of these nuclei escape into the local galactic medium they can play a significant role in the energy balance there.

If the excess is interpreted as continuous it can be produced by bremsstrahlung emission of fast 10 MeV electrons. Much less energy deposit in these electrons is necessary (∼ 10³⁶ erg s⁻¹) to generate the observed Orion flux. The intensity of these electrons even near Earth can be higher than that of the galactic cosmic ray electrons.