Diffuse cosmic rays shining in the Galactic center: A novel interpretation of H.E.S.S. and Fermi-LAT γ\gamma-ray data

Feb 3, 2017
5 pages
Published in:
  • Phys.Rev.Lett. 119 (2017) 3, 031101
  • Published: Jul 17, 2017
e-Print:
Report number:
  • CERN-TH-2017-034
Experiments:

Citations per year

2017201920212023202402468101214
Abstract: (APS)
We present a novel interpretation of the γ-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: We extend down to a few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the central molecular zone. Although we confirm the presence of a residual radial-dependent emission associated with a central source, the relevance of the large-scale diffuse component prevents to claim a solid evidence of GC pevatrons.
Note:
  • 5 pages, 3 figures, accepted for publication in Physical Review Letters
  • cosmic radiation: primary
  • galaxy
  • GLAST
  • HESS
  • position dependence
  • transport theory
  • power spectrum
  • background
  • diffusion
  • gamma ray