Detection of Two TeV Shell-type Remnants at GeV Energies with FERMI LAT: HESS J1731-347 and SN 1006

We report the first high-significance GeV gamma-ray detections of supernova remnants HESS J1731-347 and SN 1006, both of which have been previously detected by imaging atmospheric Cherenkov Telescopes above 1 TeV. Using 8 years of Fermi-LAT Pass 8 data at energies between 1 GeV and 2 TeV, we detect emission at the position of HESS. J1731-347 with a significance of similar to 5 sigma and a spectral index of Gamma= 1.66 +/- 0.16(stat) +/- 0.12(syst). The hardness of the index and the good connection with the TeV spectrum of HESS J1731-347 support an association between the two sources. We also confirm the detection of SN. 1006 at similar to 6 sigma with a spectral index of Gamma= 1.79 +/- 0.17(stat) +/- 0.27(syst). The northeast (NE) and southwest (SW) limbs of SN. 1006 were also fit separately, resulting in the detection of the NE region (Gamma= 1.47 +/- 0.26(stat)) and the non-detection of the SW region. The significance of different spectral components for the two limbs is 3.6 sigma, providing first indications of an asymmetry in the GeV gamma-ray emission.