2008ApJ...681..515G

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 E{dot}=5.5x10³⁶ ergs/s, characteristic age τ_c≡P/2P{dot}=23 kyr, and surface dipole magnetic field strength B_s=1.9x10¹² 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 X-ray 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 L_PSR=4.6x10³⁴ d²_6.6 ergs/s and L_PWN=5.2x10³³ d²_6.6 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 RSGC 1 may have given birth to one or both pulsars, while fueling TeV emission from the extended PWN with target photons for inverse Compton scattering.