Angular Broadening of Nearby Pulsars
  We conducted a very long baseline interferometric observation of 5 nearby pulsars and did not resolve the scattering disks of any of these sources. Using our upper limits on the angular diameters of these scattering disks and published values of the broadening times and proper motion velocities, we constrain the possible distributions of scattering material. The material responsible for scattering these sources is neither uniformly distributed nor concentrated at the surface of the Local Bubble. We argue that these pulsars themselves influence their environments to produce this scattering material. 
M. C. Britton, C. R. Gwinn, and M. J. Ojeda