Suzaku Observation of HESS J 1825 − 137 : Discovery of Largely - Extended X - rays near

We observed the brightest part of HESS J1825−137 with the Suzaku XIS, and found diffuse X-rays extending at least up to 15 (∼ 17 pc) from the pulsar PSR J1826−1334. The spectra have no emission line, and are fitted with an absorbed power-law model. The X-rays, therefore, are likely due to synchrotron emission from a pulsar wind nebula. The photon index near at 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 ∼ 7 μG. If the electrons are accelerated at the pulsar, the electrons must be transported over 17 pc in the synchrotron life time of 1900 yr, with a velocity of ≥ 8.8× 10 km s.