2021/01/01 by Giada Peron, F. Aharonian, Felix Aharonian +4 · 24 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #COSMIC cancer database #Cosmic ray #Fermi Gamma-ray Space Telescope #Galactic Center #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma ray #Molecular cloud #Physics #Stars #Ultra-high-energy cosmic ray #astro-ph.HE
paper · pdf · doi:10.3847/2041-8213/abcaa9
published in The Astrophysical Journal Letters 907(1), L11 (IOP Publishing)
openalex publication_date 2021/01/01 · arxiv created 2021/03/22 · arxiv updated 2021/03/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The galactic diffuse γ -ray emission, as seen by Fermi Large Area Telescope (LAT), shows a sharp peak in the region around 4 kpc from the Galactic center, which can be interpreted either as due to an enhanced density of cosmic-ray accelerators or to a modification of the particle diffusion in that region. Observations of γ -rays originating in molecular clouds are a unique tool to infer the cosmic-ray density point by point, in distant regions of the Galaxy. We report here the analysis of 11 yr Fermi-LAT data, obtained in the direction of nine molecular clouds located in the 1.5–4.5 kpc region. The cosmic-ray density measured at the locations of these clouds is compatible with the locally measured one. We demonstrate that the cosmic-ray density gradient inferred from the diffuse gamma-ray emission is the result of the presence of cosmic-ray accelerators rather than a global change of the sea of Galactic cosmic rays due to their propagation.