The extended gamma-ray source MGRO J1908+06, discovered by the Milagro air shower detector in 2007, has been observed for ~4?years by the ARGO-YBJ experiment at TeV energies, with a statistical significance of 6.2 standard deviations. The peak of the signal is found at a position consistent with the pulsar PSR J1907+0602. Parameterizing the source shape with a two-dimensional Gauss function, we estimate an extension of σext = 049 ± 022, which is consistent with a previous measurement by the Cherenkov Array H.E.S.S. The observed energy spectrum is dN/dE = 6.1 ± 1.4 × 10–13 (E/4?TeV)–2.54 ± 0.36 photons cm–2?s–1?TeV–1, in the energy range of ~1-20?TeV. The measured gamma-ray flux is consistent with the results of the Milagro detector, but is ~2-3?times larger than the flux previously derived by H.E.S.S. at energies of a few TeV. The continuity of the Milagro and ARGO-YBJ observations and the stable excess rate observed by ARGO-YBJ and recorded in four?years of data support the identification of MGRO J1908+06 as the steady powerful TeV pulsar wind nebula of PSR J1907+0602, with an integrated luminosity over 1?TeV ~ 1.8?times the luminosity of the Crab Nebula.
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