Speaker
Description
The escape process of particles accelerated at supernova remnant (SNR) shocks is here studied with a phenomenological approach which allows to quantify its impact on the CR spectrum observed on Earth as well as on the gamma-ray spectral signatures emerging from these sources. Under the assumption that in the spatial region immediately outside of the remnant the diffusion coefficient is suppressed with respect to the average Galactic one, we show that a significant fraction of particles are still located inside the SNR long time after their nominal release from the acceleration region. This fact results into a gamma-ray spectrum arising from hadronic collisions that resembles a broken power law, similar to those observed in several middle-aged SNRs. Above the break, the spectral steepening is determined by the diffusion coefficient outside of the SNR and by the time dependence of maximum energy. Consequently, the comparison between the model prediction and data will possibly allow to determine these two quantities. We also calculate the spectrum of run-away particles injected into the Galaxy by SNRs and compare it with the CR electron and proton spectra measured at Earth, which suggest that electrons are injected with a spectrum steeper than protons for energies above ~ 10 GeV.
Keywords
Supernova remnants; gamma rays; cosmic rays
| Subcategory | Theoretical Results |
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