On New X-ray Features of the Vela Pulsar Wind Nebula

Pulsar wind nebulae are the nearest space laboratories to Earth for studying a collisionless, strongly magnetized electron-positron plasma. One way to study this plasma is to construct relativistic magnetohydrodynamic (MHD) models of nebulae. These models aim to reveal, among other things, the nature of MHD structures in highly magnetized nebular flows responsible for the appearance of various features in X-ray images of nebulae—arcs, jets, tori, and so on. This paper examines the predictive potential of a recently constructed MHD model of a compact pulsar wind nebula with a double-torus X-ray morphology. The model predicts the following. Within the volume of a compact double-torus nebula, flows of highly magnetized plasma should be relativistic and quasi-laminar and may form regular folds. As they approach the outer boundary of the double torus, these flows should split into two parts. Large-scale plumes of magnetic plasma, splitting off from these flows toward the nebula’s equator, can sporadically penetrate into the opposite hemisphere of the nebula, where the plasma has reversed magnetic polarity. The base of the nebula’s leeward jet should be surrounded by a regular, toroidal magnetic vortex. We show that these predictions are supported by archival Chandra observations of Vela, the double-torus nebula of the pulsar PSR J0835–4510. The model also explains the origin of some of the diffuse X-ray emission around the double-torus of Vela.