Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope
We report the results from a detailed g ray investigation in the field of two "dark accelerators" HESS J1745 303 and HESS J1741 302, with 6.9 years of data obtained by the Fermi Large Area Telescope. For HESS J1745 303, we found that its MeV GeV emission is mainly originated from the "Region A" of the TeV feature. Its g ray spectrum can be modeled with a single power law with a photon index of 2.5 from few hundreds MeV to TeV. Moreover, an elongated feature, which extends from "Region A" toward northwest for 1.3 is discovered for the first time. The orientation of this feature is similar to that of a large scale atomic/molecular gas distribution. For HESS J1741 302, our analysis does not yield any MeV GeV counterpart for this unidentified TeV source. On the other hand, we have detected a new point source, Fermi J1740.1 3013, serendipitously. Its spectrum is apparently curved which resembles that of a g ray pulsar. This makes it possibly associated with PSR B1737 20 or PSR J1739 3023.