Scan-based observations of the Galactic plane and continuing re-observations of known very-high-energy (VHE) gamma-ray sources with the H.E.S.S. system of imaging atmospheric Cherenkov telescopes have revealed a wide variety of new VHE objects. While in many cases these objects can be associated with known sources in the X-ray, radio, or optical wavebands, a subset of them currently have no obvious cataloged lower-energy counterpart. Since at least weak X-ray and radio emission is predicted by most common VHE emission models, the lack of lower-energy detections may provide substantial model constraints and may even point to a new class of objects which emit primarily in the VHE energy range. An analysis of 8 such unidentified sources will be presented here, including a multi-wavelength discussion.

HESS Collaboration

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 2 (OG part 1), pages 621-624