Discovery of a Young, Energetic 70.5 Ms Pulsar Associated with the Tev Gamma-ray Source Hess J1837−069

We report the discovery of 70.5 ms pulsations from the X-ray source AX J1838.0−0655 using the Rossi X-ray Timing Explorer (RXTE ). PSR J1838−0655 is a rotation-powered pulsar with spin-down luminosity Ė = 5.5×10 ergs s, characteristic age τc ≡ P/2Ṗ = 23 kyr, and surface dipole magnetic field strength Bs = 1.9×10 12 G. It coincides with an unresolved INTEGRAL source and the extended TeV source HESS J1837−069. At an assumed distance of 6.6 kpc by association with an adjacent massive star cluster, the efficiency of PSR J1838−0655 converting spin-down luminosity to radiation is 0.8% for the 2−10 keV ASCA flux, 9% for the 20−300 keV INTEGRAL flux and ∼ 3% for the > 200 GeV emission of HESS J1837−069, making it a plausible power source for the latter. A Chandra Xray observation resolves AX J1838.0−0655 into a bright point source surrounded by a ≈ 2 diameter, centrally peaked nebula. The spectra of the pulsar and nebula are each well fitted by power laws, with photon indices Γ = 0.5(0.3−0.7) and Γ = 1.6(1.1−2.0), respectively. The 2−10 keV X-ray luminosities of the pulsar and nebula are LPSR = 4.6× 10 34 d6.6 ergs s −1 and LPWN = 5.2 × 10 33 d6.6 ergs s . A second X-ray source adjacent to the TeV emission, AX J1837.3−0652, is resolved into an apparent pulsar/PWN; it may also contribute to HESS J1837−069. The star cluster RSGC1 may have given birth to one or both pulsars, while fueling TeV emission from the extended PWN with target photons for inverse Compton scattering. Subject headings: pulsars: individual (AX J1838.0−0655, AX J1837.3−0652, PSR J1838−0655) — stars: neutron — supernova remnants — X-rays: stars