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Nonthermal Emission from the Arches Cluster (G0.121+0.017) and the Origin of $γ$-ray Emission from 3EG J1746-2851

F. Yusef-Zadeh·M. Nord·M. Wardle·C. Law·C. Lang·T. J. W. Lazio
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Abstract

High resolution VLA observations of the Arches cluster near the Galactic center show evidence of continuum emission at $λ$3.6, 6, 20 and 90cm. The continuum emission at $λ$90cm is particularly striking because thermal sources generally become optically thick at longer wavelengths and fall off in brightness whereas non-thermal sources increase in brightness. It is argued that the radio emission from this unique source has compact and diffuse components produced by thermal and nonthermal processes, respectively. Compact sources within the cluster arise from stellar winds of mass-losing stars (Lang, Goss & Rodriguez 2001a) whereas diffuse emission is likely to be due to colliding wind shocks of the cluster flow generating relativistic particles due to diffuse shock acceleration. We also discuss the possibility that $γ$-ray emission from 3EG J1746--2851, located within 3.3$'$ of the Arches cluster, results from the inverse Compton scattering of the radiation field of the cluster.

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F. Yusef-Zadeh, M. Nord, M. Wardle, C. Law, C. Lang, T. J. W. Lazio. 2003-05-16. Nonthermal Emission from the Arches Cluster (G0.121+0.017) and the Origin of $γ$-ray Emission from 3EG J1746-2851. https://doi.org/10.1086/376854

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