The Crab Nebula: 3-dimensional Modeling
  We construct an axisymmetric model for the Crab Nebula. The flow dyamics is based on the model by Kennel and Coroniti (1984), but we assume that the kinetic-energy-dominant wind is confined in the equatorial region. We reproduce spacially resolved spectra which agree well with the Chandra results. However, the reproduced image is not a ring but lip-shaped. In addition, brightness contrast between fore and back sides of the ring cannot be reproduced if we assumes that the sigma-parameter is as small as 10**-3. We suggest that the nebula field is highly disordered due to for instance magnetic reconnection. The estimate of sigma can be larger than previously expected. 
S. Shibata (1), H. Tomatsuri (1), M. Shimanuki (1), K. Saito (1), Y.   Nakamura (1), K. Mori (2) ((1) Yamagata University, J...