Young Energetic Psr J1617–5055, Its Underluminous Nebula and Unidentified Tev Source Hess J1616–508

We observed the young energetic pulsar J1617−5055 with the Chandra ACIS detector for 60 ks. In addition to the pulsar, the X-ray images show a faint pulsar-wind nebula (PWN) seen up to ∼ 1′ from the pulsar. Deconvolution and reconstruction of the image reveal a brighter compact PWN component of ∼ 1′′ size, possibly with a jet-torus morphology. The PWN spectrum fits an absorbed power-law (PL) model with the photon index Γ≈ 1.5. The total PWN luminosity in the 0.5–8 keV band, Lpwn = 3.2×1033 ergs s−1 for d = 6.5 kpc, is a fraction of 2×10−4 of the pulsar’s spin-down power Ė and a fraction of 0.2 of the pulsar’s X-ray luminosity, which is a factor of 20 lower than one would expect from an average empirical relation found for a sample of PWNe observed with Chandra. The pulsar’s spectrum can be described by an absorbed PL with nH ≈ 3.5×1022 cm−2 and Γ≈ 1.1, harder than any other pulsar spectrum reliably measured in the soft X-ray band. This non-thermal emission is ≈ 50% pulsed showing one peak per period. We have also investigated a possible connection between J1617 and the extended TeV source HESS J1616–508 whose center is located 10′ west of the pulsar. We find no preferential extension of the X-ray PWN toward the TeV source. Therefore, the Chandra data do not provide conclusive evidence for PSR J1617–5055 and HESS J1616–508 association. We have also analyzed archival X-ray, radio, and IR data on the HESS J1616–508 region and found traces of diffuse emission (resembling a shell in the radio) coinciding with the central part of HESS J1616–508. We speculate that the TeV source may be multiple, with most of the emission coming from an unknown SNR or a star-forming region, while some fraction of the TeV emission still may be attributed to the J1617 PWN. Subject headings: ISM: individual (HESS J1616−508) — pulsars: individual (PSR J1617−5055) — stars: neutron — X-rays: ISM