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Origin of quasi-harmonic emission bands with fine structure in the dynamic spectra of high-frequency interpulses of the Crab pulsar
We study the origin of quasi-harmonic emission bands with fine structure observed in the
dynamic radiation spectra of high-frequency interpulses. The possible explanation of observed
structure is based on the effect of double plasma resonance (DPR) at electron cyclotron
harmonics realized in the magnetosphere of pulsar in a local radio emission source filled
with non-relativistic plasma. The model of the source consists of neutral current sheet with a
transversemagnetic field where plasma waves are generated due to DPR effect. It is shown that
the emergence of emission bands and their frequency spacing are due to the inhomogeneity
of the plasma and magnetic field along the current sheet, and their fine structure is due to
the inhomogeneity of the current sheet in the direction orthogonal to it. Each quasi-harmonic
emission band represents a system of elements of fine features of radiation that is generated by
suprathermal electrons under DPR conditions. The observed upward drift of quasi-harmonic
emission bands is due to the displacement of suprathermal electrons across the current sheet
and an increase in the DPR frequencies with distance from the central plane of the layer.