On the mean profiles of radio pulsars - I. Theory of propagation effects

We study the influence of the propagation effects on the mean profiles of radio pulsars using the method of the wave propagation in the inhomogeneous media de-scribing by Kravtsov & Orlov (1990). This approach allows us firstly to include into consideration the transition from geometrical optics to vacuum propagation, the cy-clotron absorption, and the wave refraction simultaneously. In addition, non-dipole magnetic field configuration, drift motion of plasma particles, and their realistic en-ergy distribution are taken into account. It is confirmed that for ordinary pulsars (period P ∼ 1 s, surface magnetic field B0 ∼ 1012 G) and typical plasma generation near magnetic poles (the multiplicity parameter λ = ne/nGJ ∼ 103) the polarization is formed inside the light cylinder at the distance resc ∼ 1000R from the neutron star, the circular polarization being 5–20 % which is just observed. The one-to-one correspondence between the signs of circular polarization and position angle (p.a.) derivative along the profile for both ordinary and extraordinary waves is predicted. Using numerical integration we now can model the mean profiles of radio pulsars. It is shown that the standard S-shape form of the p.a. swing can be realized for small enough multiplicity λ and large enough bulk Lorentz factor γ only. It is also shown that the value of p.a. maximum derivative, that is often used for determination the angle between magnetic dipole and rotation axis, depends on the plasma parameters and could differ from the rotation vector model (RVM) prediction. Key words: Neutron stars — radio pulsars — polarization 1

Перевод пока недоступен