DOI: 10.1093/mnras/stad2624 ISSN:

A dual-zone diffusion model for high energy emissions of the cygnus cocoon

Shihong Zhan, Wei Wang
  • Space and Planetary Science
  • Astronomy and Astrophysics


As one of the brightest galactic γ-ray sources, the Cygnus Cocoon superbubble has been observed by many detectors, such as Fermi-LAT, ARGO, HAWC, and LHAASO. However, the origin of γ-ray emission for the Cygnus Cocoon and the possible contribution to PeV cosmic rays are still under debate. The recent ultrahigh-energy γ-ray observations by LHAASO up to 1.4 PeV towards the direction of the Cygnus Cocoon, as well as the neutrino event report of IceCube-201120A coming from the same direction, suggest that the Cygnus Cocoon may be one of the sources of high-energy cosmic rays in the Galaxy. In this work, we propose a dual-zone diffusion model for the Cygnus Cocoon: the cocoon region and surrounding interstellar medium (ISM). This scenario can account for the γ-ray data from GeV to ∼ 50 TeV and agree with the one sub-PeV neutrino event result from IceCube so far. Moreover, it predict a non-negligible contribution γ-ray emission at hundreds TeV from the ISM surrounding the Cygnus Cocoon. This possible diffuse TeV-PeV gamma-ray features can be resolved by the future LHAASO observations.

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