Discovery of two candidate pulsar wind nebulae in very-high-energy gamma rays

Context.We present the discovery of two very-high-energy $\gamma$-ray sources in an ongoing systematic search for emission above 100 GeV from pulsar wind nebulae in survey data from the HESS telescope array. Aims.Imaging Atmospheric Cherenkov Telescopes are ideal tools for searching for extended emission from pulsar wind nebulae in the very-high-energy regime. HESS, with its large field of view of 5$^{\circ}$ and high sensitivity, gives new prospects for the search for these objects. Methods.An ongoing systematic search for very-high-energy emission from energetic pulsars over the region of the Galactic plane between $-60^\circ < l < 30^\circ$, $-2^\circ < b < 2^\circ$ is performed. For the resulting candidates, the standard HESS analysis was applied and a search for multi-wavelength counterparts was performed. Results. We present the discovery of two new candidate $\gamma$-ray pulsar wind nebulae, HESS J1718-385 and HESS J1809-193. Conclusions.HESS has proven to be a suitable instrument for pulsar wind nebula searches.