Evidence for Extended High-Energy Gamma-Ray Emission from the Rosette/Monoceros Region

We present an image reconstruction of the region around the Rosette Nebula and Monoceros Supernova Remnant (SNR) using high-energy (>100 MeV) γ-ray data from EGRET. The method uses a multiresolution support and wavelet-based noise-suppression algorithm that looks for extended structure in addition to pointlike features (Murtagh et al.). The resulting image shows a 7 σ extended feature in excess of the expected diffuse emissions located at the point-source position listed in the EGRET catalog. This feature overlaps both the Monoceros SNR and the nearby Rosette Nebula and correlates with emission at other wavelengths. The γ-ray emission may be additional evidence of an interaction between the Monoceros remnant and the Rosette Nebula.