Diffuse galactic gamma-ray emission with H.E.S.S.
Date
2014Author
Abramowski, A.
Böttcher, M.
Davids, I.D.
Ivascenko, A.
Kruger, P.P.
Pekeur, N.W.
Spanier, F.
Sushch, I.
Venter, C.
Vorster, M.
H.E.S.S. Collaboration
Metadata
Show full item recordAbstract
Diffuse γ-ray emission is the most prominent observable signature of celestial cosmic-ray interactions at
high energies. While already being investigated at GeVenergies over several decades, assessments of diffuse
γ-ray emission at TeVenergies remain sparse. After completion of the systematic survey of the inner Galaxy,
the H.E.S.S. experiment is in a prime position to observe large-scale diffuse emission at TeVenergies. Data of
the H.E.S.S. Galactic Plane Survey are investigated in regions off known γ-ray sources. Corresponding γ-ray
flux measurements were made over an extensive grid of celestial locations. Longitudinal and latitudinal
profiles of the observed γ-ray fluxes show characteristic excess emission not attributable to known γ-ray
sources. For the first time large-scale γ-ray emission along the Galactic plane using imaging atmospheric
Cherenkov telescopes has been observed. While the background subtraction technique limits the ability to
recover modest variation on the scale of the H.E.S.S. field of view or larger, which is characteristic of the
inverse Compton scatter-induced Galactic diffuse emission, contributions of neutral pion decay as well as
emission from unresolved γ-ray sources can be recovered in the observed signal to a large fraction.
Calculations show that the minimum γ-ray emission from π0 decay represents a significant contribution to the
total signal. This detection is interpreted as a mix of diffuse Galactic γ-ray emission and unresolved sources
URI
http://hdl.handle.net/10394/32084https://journals.aps.org/prd/abstract/10.1103/PhysRevD.90.122007
https://doi.org/10.1103/PhysRevD.90.122007