1999/07/20 by T. Oka, Tomoharu Oka, N. Kawai +8 · 3 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/308014
To appear in ApJ, 14 pages, 5 figures
arxiv created 1999/07/20 · openalex publication_date 1999/12/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
CO J = 1-0 mapping observations of the dark nebula Lynds 227, which is possibly associated with the unidentified EGRET source 2EG J1811-2339, are presented. We detected a large amount of molecular gas along Lynds 227 with a total mass of (1-2) × 10 4 M ☉ surrounding an X-ray synchrotron nebula, which was detected by the ASCA within the error circle of 2EG J1811-2339. Molecular gas along Lynds 227 shows spatial anticorrelation with the X-ray synchrotron nebula, suggesting that the synchrotron nebula is interacting with the Lynds 227 cloud. We propose a γ-ray emission mechanism for 2EG J1811-2339: high-energy electrons are injected from a rotation-powered pulsar and further accelerated in shock waves generated by the interaction with ambient matter. The high-energy electrons move into the molecular cloud at the Lynds 227 and collide with dense interstellar matter to yield high-energy γ-ray photons, mainly through relativistic bremsstrahlung.