Two tori of the Vela pulsar wind nebula

In the frame of the axisymmetric relativistic magnetohydrodynamic simulations we show that the double-arc feature of the Vela pulsar wind nebula (PWN) visible in soft X-rays can be reproduced at high inclination (obliquity) of the Vela pulsar and low magnetization of its wind provided the turbulent and magnetic energies of the nebula dissipate effectively. In that case, the arcs represent the Doppler brightened regions of two persistent large-scale toroidal whirls of strongly magnetized plasma located below and above the wide low-magnetized equatorial belt of the nebula. If the long-term persistence of the large-scale magnetic structures would be confirmed in more realistic simulations, the difference in X-ray morphology of the Crab and Vela PWNe can be explained by the difference in spin-down and inclination of their parent pulsars, and not by the very different magnetization of their winds, as supposed earlier.