2002ApJ...572L..91L

Radio pulses emitted from a pulsar magnetosphere travel across the light cylinder and through a magnetized relativistic pulsar wind composed mainly of an electron-positron (e^{mnplus}) pair plasma embedded in a spiral magnetic field. Besides the Doppler-shifted cyclotron resonance and wind advections of hybrid oscillations or low-frequency waves, we identify two cutoff frequencies at ω_pe and ~(ω²_pe+ω²_c/γ²)^1/2 for radio waves of two orthogonal polarizations perpendicular and parallel to the projected spin axis in the sky plane, where ω_pe is the proper e^{mnplus} pair plasma frequency, ω_c is the relativistic Larmor frequency, and γ is the Lorentz factor of e^{mnplus} bulk flow. Radio pulse spectra of most pulsars show low-frequency cutoffs at ν_cut≲100 MHz. For (ω²_pe+ω²_c/γ²)^1/2<2πν_cut, one may bracket the e^{mnplus} particle loss rate of a pulsar wind. If for some cases, alternative to the wisdom that all such spectral cutoffs are intrinsic to the emission mechanism(s) near a pulsar, the magnetized e^{mnplus} pair plasma of a pulsar wind actually causes the low-frequency cutoffs of radio pulse spectra, then spectral polarization studies of the two different frequency cutoffs can yield ω_pe and ω_c/γ. Together with the observed rates of pulsar spin and spin-down, one may derive key properties of a pulsar wind, including the e^{mnplus} particle loss rate.