A search for very high energy gamma-ray emission from the starburst galaxy NGC253 with HESS

We present the result of 28 h of observations of the nearby starburst galaxy NGC 253 with the HESS$\,$detector in 2003. We find no evidence for very high energy $\gamma$-ray emission from this object. Gamma-ray emission above 400 GeV from NGC 253 had been reported by the CANGAROO collaboration in 2002. From the HESS$\,$data we derive upper limits on the flux above 300 GeV of $1.9\,\times\,10^{-12}$ photons cm-2 s-1 for a point-like source and $6.3\,\times\,10^{-12}$ photons cm-2 s-1 for a source of radius 0.5$^{\circ}$ as reported by CANGAROO, both at a confidence level of 99%. These upper limits are inconsistent with the spectrum reported by CANGAROO. The expected very high energy $\gamma$-ray emission from this object is discussed in the framework of a galactic wind propagation model.