The H.E.S.S .
collaboration has discovered a new very high energy ( VHE , E > 0.1 TeV ) \gamma -ray source , HESS J1741 - 302 , located in the Galactic plane .
Despite several attempts to constrain its nature , no plausible counterpart has been found so far at X-ray and MeV/GeV \gamma -ray energies , and the source remains unidentified .
An analysis of 145-hour of observations of HESS J1741 - 302 at VHEs has revealed a steady and relatively weak TeV source ( \sim 1 \% of the Crab Nebula flux ) , with a spectral index of \Gamma = 2.3 \pm 0.2 _ { \text { stat } } \pm 0.2 _ { \text { sys } } , extending to energies up to 10 TeV without any clear signature of a cut-off .
In a hadronic scenario , such a spectrum implies an object with particle acceleration up to energies of several hundred TeV .
Contrary to most H.E.S.S .
unidentified sources , the angular size of HESS J1741 - 302 is compatible with the H.E.S.S .
point spread function at VHEs , with an extension constrained to be below 0.068 ^ { \circ } at a 99 \% confidence level .
The \gamma -ray emission detected by H.E.S.S .
can be explained both within a hadronic scenario , due to collisions of protons with energies of hundreds of TeV with dense molecular clouds , and in a leptonic scenario , as a relic pulsar wind nebula , possibly powered by the middle-aged ( 20 kyr ) pulsar PSR B1737 - 30 .
A binary scenario , related to the compact radio source 1LC 358.266 + 0.038 found to be spatially coincident with the best fit position of HESS J1741 - 302 , is also envisaged .