Suzaku Observation of HESS J1825-137: Discovery of Largely-Extended X-Rays from PSR J1826-1334

Abstract

We observed the brightest part of HESS J1825-137 with the Suzaku XIS, and found diffuse X-rays extending at least up to 15' (∼17pc) from the PSR J1826-1334. The spectra have no emission line, and were fitted with an absorbed power-law model. The X-rays, therefore, are likely to be due to synchrotron emission from a pulsar wind nebula. The photon index near the pulsar (r≤ 1.'5) is Γ = 1.7, while those in r = 1.'5--16' are nearly constant at Γ = 2.0. The spectral energy distribution of the Suzaku and H.E.S.S. results are naturally explained by a combined process; synchrotron X-rays and γ-rays by the inverse Compton of the cosmic microwave photons by high-energy electrons in a magnetic field of ∼7μG. If the electrons are accelerated at the pulsar, the electrons must be transported over 17 pc in the synchrotron lifetime of 1900yr, with a velocity of ≥8.8 × 10³ km s^-1.