Discovery of a Radio Supernova Remnant and Nonthermal X-Rays Coincident with the TeV Source HESS J1813-178

We present the discovery of non-thermal radio and X-ray emission positionallycoincident with the TeV $\gamma$-ray source HESS J1813--178. We demonstratethat the non-thermal radio emission is due to a young shell-type supernovaremnant (SNR) G12.8--0.0, and constrain its distance to be greater than 4 kpc.The X-ray emission is primarily non-thermal and is consistent with either anSNR shell or unidentified pulsar/pulsar wind nebula origin; pulsed emission isnot detected in archival ASCA data. A simple synchrotron+inverse Compton modelfor the broadband emission assuming that all of the emission arises from theSNR shell implies maximum energies of $(30-450)(B/10 microG)^{-0.5}$ TeV.Further observations are needed to confirm that the broadband emission has acommon origin and better constrain the X-ray spectrum.Comment: Accepted to ApJ Letters; 5 pages, Figures 1 and 3 are in color. Small changes from original versio