This project will study the sizes and shapes of pulsar emission regions, using interstellar scattering as a lens. It will derive the sizes and elongations of the emission region of the Vela pulsar as a function of pulse phase, providing images or a short movie over sizes of a few hundred kilometers, and improving understanding of pulsar emission. The project will advance the mathematical description of signals from a scattered source, and should lead to improvements in correlators. The work includes 1) installing a software correlator to study and correct for effects of de-dispersion, digitization, and pulsar gating; 2) improving and extending mathematical models for the intensity and interferometric visibility of small scintillating sources, including the effects of noise; 3) measuring the variation of source size, elongation, and position angle as a function of pulse phase, for the Vela pulsar; and 4) measuring, or at least setting limits on, the sizes of emission regions of older, slower pulsars.
This work will form the bulk of a graduate student's thesis, and will include undergraduate physics majors via theses and summer projects. Through a weekend science program, the project will also introduce local high-school students to conversion of sound to electricity and back, and to signal processing by computer to supplement the ear and brain in deciphering sound.
