Gamma-Ray Emission from Molecular Clouds Generated by Penetrating Cosmic Rays
| Autor: | V. A. Dogiel, A. V. Ivlev, K. S. Cheng, Andrew W. Strong, D. Malyshev, Dmitrii Chernyshov |
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| Rok vydání: | 2018 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Physics Range (particle radiation) 010308 nuclear & particles physics Scattering Astrophysics::High Energy Astrophysical Phenomena Molecular cloud Galactic Center Gamma ray FOS: Physical sciences Flux Astronomy and Astrophysics Cosmic ray Astrophysics 01 natural sciences Standard Model Space and Planetary Science 0103 physical sciences Astrophysics - High Energy Astrophysical Phenomena 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics |
| Zdroj: | The Astrophysical Journal. 868:114 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aae827 |
| Popis: | We analyze the processes governing cosmic-ray (CR) penetration into molecular clouds and the resulting generation of gamma-ray emission. The density of CRs inside a cloud is depleted at lower energies due to the self-excited MHD turbulence. The depletion depends on the effective gas column density ("size") of the cloud. We consider two different environments where the depletion effect is expected to be observed. For the Central Molecular Zone, the expected range of CR energy depletion is $E\lesssim 10$ GeV, leading to the depletion of gamma-ray flux below $E_\gamma\approx 2$ GeV. This effect can be important for the interpretation of the GeV gamma-ray excess in the Galactic Center, which has been revealed from the standard model of CR propagation (assuming the CR spectrum inside a cloud to be equal to the interstellar spectrum). Furthermore, recent observations of some local molecular clouds suggest the depletion of the gamma-ray emission, indicating possible self-modulation of the penetrating low-energy CRs. Comment: 10 pages, 5 figures, accepted for publication in ApJ |
| Databáze: | OpenAIRE |
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