2010ApJ...720..848T

Using the Chandra X-ray Observatory, we have pinpointed the location of a faint X-ray point source (CXOU J182913.1-125113) and an associated diffuse nebula in the composite supernova remnant (SNR) G18.95-1.1. These objects appear to be the long-sought pulsar and its wind nebula. The X-ray spectrum of the point source is best described by an absorbed power-law model with Γ = 1.6 and an N_H of ∼1x10²²/cm2. This model predicts a relatively low unabsorbed X-ray luminosity of about L_X(0.5-8.0 keV) =~ 4.1 x 10³¹ D ²₂ erg/s, where D₂is the distance in units of 2 kpc. The best-fit model of the diffuse nebula is a combination of thermal (kT = 0.48 keV) and non-thermal (1.4 ≤ Γ ≤ 1.9) emission. The unabsorbed X-ray luminosity of L_X=~ 5.4x10³³ D ²₂ erg/s in the 0.5-8 keV energy band seems to be largely dominated by the thermal component from the SNR, providing 87% of L_X in this band. No radio or X-ray pulsations have been reported for CXOU J182913.1-125113. If we assume an age of ∼5300 yr for G18.95-1.1 and use the X-ray luminosity for the pulsar and the wind nebula together with the relationship between spin-down luminosity (via magnetic dipole radiation) and period, we estimate the pulsar's period to be P =~ 0.4 s. Compared to other rotation-powered pulsars, a magnetic field of 2.2 x10¹³ G is implied by its location in the P-{dot}P diagram, a value which is close to that of the quantum critical field.