A new GeV-TeV particle component and the barrier of cosmic-ray sea in the CMZ region

Abstract

The Galactic center is widely anticipated to be an important cosmic-ray source and the observations of some Imaging Atmospheric Cherenkov Telescopes did successfully reveal a new component of TeV-PeV cosmic rays. This work reports the identification of the 80 GeV - 5 TeV cosmic rays in the CMZ region with the $\\gamma$-ray observation of the Fermi-LAT. In our analysis the GeV excess component has been taken into account and the resulting $\\gamma$-ray spectrum as well as the intensity gradient are consistent with that measured by the Imaging Atmospheric Cherenkov Telescopes. The inferred cosmic-ray energy density is however substantially lower than the so-called cosmic-ray sea component. Our finding is in support of the presence of high energy particle accelerator at the Galactic center and strongly suggests a barrier that can effectively suppress the penetration of the particles from the cosmic-ray sea.