Discovery of a Radio Supernova Remnant and Non-thermal X-rays Coincident with the TeV Source HESS J1813-178

We present the discovery of non-thermal radio and X-ray emission positionally coincident with the TeV source HESS J1813-178. We demonstrate that the non-thermal radio emission is due to a young shell-type supernova remnant (SNR) G12.8--0.0, and constrain its distance to be greater than 4 kpc. The non-thermal X-ray emission is consistent with originating from the SNR shell or an unidentified pulsar/pulsar wind nebula; pulsed emission is not detected in archival ASCA data. The X-ray emission falls on a direct extrapolation of the radio synchrotron power-law before the roll-off due to radiative losses, an unusual occurrence and remarkable coincidence if the origin of the emission is not the same (i.e. the SNR shell). Assuming that the radio and X-ray emission originate from the SNR shell we find that G12.8--0.0 accelerates electrons up to at least 450 TeV, higher than for any other SNR yet observed. A model that incorporates data spanning 18 decades in frequency suggests that inverse Compton emission off the cosmic microwave background cannot account for the TeV emission. Further observations are needed to confirm that the broadband emission has a common origin