Interstellar scattering of pulsar radiation

Electron density fluctuations in the interstellar medium scatter radio emission from pulsars. The scattered radiation that we observe on earth provides information on the strength and distribution of scattering material. Radiation scattered into our line of sight appears to originate from a scattering disk. Because of multipath propagation, rays traversing different path lengths arrive over a range of times called the broadening time. In this thesis I will describe a very long baseline interferometric (VLBI) observation of 5 nearby pulsars to measure the angular diameters of their scattering disks. We did not resolve the scattering disks of any of these sources. Using our upper limits on the angular diameters and published values of the temporal broadening 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.