A search for gamma-ray emission from the Galactic plane in the longitude range between $\mathsf{37}^\circ$ and $\mathsf{43}^\circ$

Abstract

Using the HEGRA system of imaging atmospheric Cherenkov telescopes, a region of the Galactic plane ( 10 <b< 5 ,3 8 <l< 43) was surveyed for TeV gamma-ray emission, both from point sources and of diuse nature. The region covered includes 15 known pulsars, 6 known supernova remnants (SNR) and one unidentied EGRET source. No evidence for emission from point sources was detected; upper limits are typically below 0.1 Crab units for the flux above 1 TeV. For the diuse gamma-ray flux from the Galactic plane, an upper limit of 6:1 10 15 ph cm 2 s 1 sr 1 MeV 1 was derived under the assumption that the spatial distribution measured by the EGRET instrument extends to the TeV regime. This upper flux limit is a factor of about 1.5 larger than the flux expected from the ensemble of gamma-ray unresolved Galactic cosmic ray sources.