Diffusion of cosmic-rays and the Gamma-ray Large Area Telescope: Phenomenology at the 1-100 GeV regime

Abstract

This paper analyzes astrophysical scenarios that may be detected at the upper end of the energy range of the Gamma Ray Large Area Space Telescope (GLAST), as a result of cosmic-ray (CR) diffusion in the interstellar medium (ISM). Hadronic processes are considered as the source of $\gamma$-ray photons from localized molecular enhancements nearby accelerators. Two particular cases are presented: a) the possibility of detecting spectral energy distributions (SEDs) with maxima above 1 GeV, which may be constrained by detection or non-detection at very-high energies (VHE) with observations by ground-based Cerenkov telescopes, and b) the possibility of detecting V-shaped, inverted spectra, due to confusion of a nearby (to the line of sight) arrangement of accelerator/target scenarios with different characteristic properties. We show that the finding of these signatures (in particular, a peak at the 1--100 GeV energy region) is indicative for an identification of the underlying mechanism producing the $\gamma$-rays that is realized by nature: which accelerator (age and relative position to the target cloud) and under which diffusion properties CR propagate.

In press at The Astrophysical Journal

References in corpus (7)

• First detection of a VHE gamma-ray spectral maximum from a Cosmic source: H.E.S.S. discovery of the Vela X nebula
• Gamma rays from molecular clouds
• Searching for galactic cosmic ray pevatrons with multi-TeV gamma rays and neutrinos
• Inverse Compton Scenarios for the TeV Gamma-Ray Emission of the Galactic Centre
• The Anti-Coincidence Detector for the GLAST Large Area Telescope
• MAGIC J0616+225 as delayed TeV emission of cosmic-rays diffusing from SNR IC 443
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• The GeV to TeV connection in the environment of SNR IC 443
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• Fermi-LAT detection of extended gamma-ray emission in the vicinity of SNR G045.7$-$00.4: evidence for escaping cosmic rays interacting with the surrounding molecular clouds