A Radio Counterpart for the Unidentified TeV Source HESS J1813-178: The Radio-Gamma-Ray Connection

We discovered independently the shell-type supernova remnant G12.82-0.02, recently reported by Brogan et al. (2005), which is coincident with the unidentified TeV gamma-ray source revealed in the HESS survey of the Galactic plane. Estimating the ambient starlight at the location of this source from the integrated Ly alpha luminosity of the nearby H II region W33, we conclude that inverse Compton emission is a viable explanation for the observed TeV emission. Examining remnants in the survey of Aharonian et al. (2005a) including those detected above 200 Gev and those not detected, we find a strikingly large range of more than three orders of magnitude in the radio to TeV flux ratios. We briefly explore the possible explanations of this range and the implications for the TeV emission mechanism.