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Session 23 - Degenerate Stars, Pulsars.
Display session, Tuesday, June 10
South Main Hall,

[23.01] A Statistical Model for the Orthogonal Modes of Polarization in Pulsar Radio Emission

M. M. McKinnon (NRAO), D. R. Stinebring (Oberlin College)

The radio emission from pulsars is modelled as a superposition of two modes of orthogonally polarized radiation. The polarization of each mode is assumed to be completely linear, and the flux densities of the modes are represented by random variables to account for the random switching between orthogonally polarized states. Example distributions of total intensity, linear polarization, fractional linear polarization, and polarization position angle are computed with the model. The model is compared with polarization observations of individual pulses from PSR B2020+28. Once allowances have been made for interstellar scintillation, the model distributions compare favorably with observed histograms, except for the position angle histograms which are wider than one would expect from a \delta-function that is broadened by instrumental noise. The flux densities of the orthogonal modes in PSR B2020+28 are found to be highly correlated, suggesting that the modes are not produced by independent emission mechanisms.

The depolarization of pulsar radio emission has been attributed to the orthogonal modes or to the randomization of position angle. A random, or uniform, component of the position angle will arise from superposed modes that occur with nearly equal frequency. The random component of position angle in PSR B2020+28 is shown to be a consequence of depolarization by the orthogonal modes.

Program listing for Tuesday