Chandra Observation of PSR B1823–13 and Its Pulsar Wind Nebula

An observation of the Vela-like pulsar B1823-13 and its synchrotron nebula with the Chandra X-Ray Observatory allowed us to resolve the pulsar and the fine structure of the nebula. The pulsar's spectrum fits a power-law model with a photon index [image] for the plausible hydrogen column density [image] cm super(-2), corresponding to the luminosity [image] ergs s super(- 1) in the 0.5-8 keV band, at a distance of 4 kpc. The pulsar radiation likely includes magnetospheric and thermal components, but they cannot be reliably separated, because of the small number of counts detected and strong interstellar absorption. The pulsar is surrounded by a compact, [image], pulsar wind nebula (PWN) elongated in the east-west direction, which includes a brighter inner component [sim][image], elongated in the northeast-southwest direction. The slope of the compact PWN spectrum is [image], and the 0.5-8 keV luminosity is [image] ergs s super(-1). The compact PWN is surrounded by asymmetric diffuse emission (extended PWN) seen up to at least 2.4 super([image] ) south of the pulsar, with a softer spectrum ([image] for [image] cm super(-2)), and the 0.5-8 keV luminosity [image] -10 super(34) ergs s super(-1). We also measured the pulsar's proper motion using archival VLA data, [image] mas yr super(-1) and [image] mas yr super(-1) (in LSR), which corresponds to the transverse velocity [image] km s super(-1). The direction of the proper motion is approximately parallel to the elongation of the compact PWN, but it is nearly perpendicular to that of the extended PWN and to the direction toward the center of the bright VHE -ray source HESS J1825-137, which is believed to be powered by PSR B1823-13.