RADIO PHYSICS AND RADIO ASTRONOMY

 PACS numbers: 97.60.Jd;
97.60.Gb; 52.38.Bv

Purpose: The subject of the paper is discussion of reflected radiation from the neutron star surface. Such radiation, as was shown earlier by S. V. Trofymenko and one of the authors, occurs when reflects the radiation of relativistic positrons flying from the magnetosphere to a star in the accelerating electric field of the polar gap. This gave an explanation of both the interpulse shift in the Crab pulsar (mirror reflection in an inclined magnetic field) and the appearance of additional HF components (diffraction on the periodic structure excited by the incident radiation) discovered by Moffett and Hankins. The aim of the paper is to study the effect on the HF components of a resonance with a surface electromagnetic wave.

Design/methodology/approach: Since the HF components occur at the same frequencies as the interpulse shift, we believe that they are a consequence of the same physical process. Such a process is the reflection from the surface of a neutron star of the radiation of the return positrons. The appearance of HF components is considered as a manifestation of stimulated scattering by surface waves. For comparison, the data of laboratory experiments on the diffraction of laser radiation on a metal diffraction grating are presented. They demonstrate the appearance of a bright near-surface wave under resonance conditions, which can serve as an analog of the HF component in the Crab pulsar.

Findings: In the formation of HF components, such phenomena as Wood’s anomalies are significant, leading to considerable essential increase of the increment of stimulated scattering at the resonance with the surface electromagnetic wave. The surface wave excited with the resonance leads to reflected Raman scattering of higher frequencies of the continuous spectrum of the incident radiation.

Conclusions: The radiation of a pulsar is determined, among others, by the reflecting properties of the surface of the neutron star, i.e. its conductivity (surface impedance). The resonance substantially reduces the stimulated scattering threshold. The continuous spectrum of the radiation incident on the surface provides a large width of the HF-components.

Key words: neutron star, pulsar, interim pulse, HF components, reflection, stimulated Raman scattering, diffraction, Wood anomalies

Manuscript submitted 16.07.2018

Radio phys. radio astron. 2018, 23(3): 166-175

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