Fermi Gamma-ray Space Telescope

2FHL J0826.1-45.00: Discovery of a new VHE Galactic Accelerator

Jordan Eagle
(Stefano Marchesi, Daniel Castro, Marco Ajello, Laura Duvidovich)


The discovery of a very high energy (VHE) Galactic gamma ray source was recently observed at energies above 50 GeV using the Large Area Telescope (LAT) on board Fermi. This object, 2FHL J0826.1-4500, displays one of the hardest >50 GeV spectra (photon index~1.6) in the 2FHL sample, and a follow-up observation with XMM-Newton led to the discovery of diffuse, soft thermal emission at the position of the gamma ray source. A detailed analysis of the available multi-wavelength data led to the finding that this source is located on the Western edge of the Vela supernova remnant (SNR): the observations and the spectral energy distribution modeling support a scenario where 2FHL J0826.1-4500 is the byproduct of an interaction between the front shock of the SNR and a neutral Hydrogen cloud. If confirmed, this shock-cloud interaction would make 2FHL J0826.1-4500 a promising candidate for efficient particle acceleration.