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arXiv · 1308.0161

Diffuse TeV Gamma-Ray Emission in the H.E.S.S. Galactic Plane Survey

K. Egberts·F. Brun·S. Casanova·W. Hofmann·M. de Naurois·O. Reimer·Q. Weitzel·Y. Fukui
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Abstract

Diffuse gamma-ray emission has long been established as the most prominent feature in the GeV sky. Although the imaging atmospheric Cherenkov technique has been successful in revealing a large population of discrete TeV gamma-ray sources, a thorough investigation of diffuse emission at TeV energies is still pending. Data from the Galactic Plane Survey (GPS) obtained by the High Energy Stereoscopic System (H.E.S.S.) have now achieved a sensitivity and coverage adequate for probing signatures of diffuse emission in the energy range of ~100 GeV to a few TeV. Gamma-rays are produced in cosmic-ray interactions with the interstellar medium (aka "sea of cosmic rays") and in inverse Compton scattering on cosmic photon fields. This inevitably leads to guaranteed gamma-ray emission related to the gas content along the line-of-sight. Further contributions relate to those gamma-ray sources that fall below the current detection threshold and the aforementioned inverse Compton emission. Based on the H.E.S.S. GPS, we present the first observational assessment of diffuse TeV gamma-ray emission. The observation is compared with corresponding flux predictions based on the HI (LAB data) and CO (as a tracer of H2, NANTEN data) gas distributions. Consequences for unresolved source contributions and the anticipated level of inverse Compton emission are discussed.

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K. Egberts, F. Brun, S. Casanova, W. Hofmann, M. de Naurois, O. Reimer, Q. Weitzel, Y. Fukui. 2013-08-01. Diffuse TeV Gamma-Ray Emission in the H.E.S.S. Galactic Plane Survey. https://arxiv.org/abs/1308.0161

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