BEXCO - Room C(108)
[GA031] Contribution to diffuse gamma-ray emission coming from self-confined CRs around their Galactic sources
In this work we estimate the gamma-ray emission from hadronic interactions produced by cosmic rays (CR) accelerated in Galactic sources that remain confined around their sources for a time longer than the one estimated using the average Galactic diffusion coefficient. The confinement is due to magnetic turbulence that CRs self-produce during the escaping process in a region around the source where the density of freshly accelerated CRs is larger than the average Galactic one. The length of such a region is typically of the order of the coherence length of the large scale magnetic field (Lc ~ 50-100 pc). One consequence of this confinement is the creation of extended halos of enhanced gamma-ray emission around the sources. The gamma-ray flux from a single halo is generally too low to be detected by current gamma-ray telescopes, nevertheless we show that the sum over all halos can give a non negligible contribution to the diffuse Galactic emission, comparing our calculation with the Fermi-LAT data collected over the past 7 years. We also account for the presence of neutral H atoms which damp the magnetic turbulence through the ion-neutral friction. Even if this effect reduces the efficiency of the self-confinement, we show that the contribution to diffuse gamma-ray emission coming from the near-source regions remains non negligible especially for photon energies >~ 100 GeV.