2011ApJ...729L..16G

We report the discovery of a 38.5 ms X-ray pulsar in observations of the soft γ-ray source IGR J18490-0000 with the Rossi X-ray Timing Explorer (RXTE). PSR J1849-0001 is spinning down rapidly with period derivative 1.42 x10^–14 s/s, yielding a spin-down luminosity {dot}E = 9.8x10³⁶ erg/s, characteristic age τ_c ≡P/2{dot}P = 42.9 kyr, and surface dipole magnetic field strength B_s= 7.5x10¹¹ G. Within the INTEGRAL/IBIS error circle lies a point-like XMM-Newton and Chandra X-ray source that shows evidence of faint extended emission consistent with a pulsar wind nebula (PWN). The XMM-Newton spectrum of the point source is well fitted by an absorbed power-law model with photon index Γ_PSR= 1.1±0.2, N_H= (4.3±0.6)x10²²/cm2, and F_PSR(2-10 keV) = (3.8±0.3)x10^–12 erg/cm2/s, while the spectral parameters of the extended emission are roughly Γ_PWN~ 2.1 and F_PWN(2-10 keV) ~ 9x10^–13 erg/cm2/s. IGR J18490-0000 is also coincident with the compact TeV source HESS J1849-000. For an assumed distance of 7 kpc in the Scutum arm tangent region, the 0.35-10 TeV luminosity of HESS J1849-000 is 0.13% of the pulsar's spin-down energy, while the ratio F(0.35-10 TeV)/F_PWN(2-10 keV) ~ 2. These properties are consistent with leptonic models of TeV emission from PWNe, with PSR J1849-0001 in a stage of transition from a synchrotron X-ray source to an inverse Compton γ-ray source.