Polarized emission from of an off-centred dipole

Abstract

Radio polarization measurements of pulsed emission from pulsars offer a valuable insight into the basic geometry of the neutron star: inclination angle between the magnetic and rotation axis and inclination of the line of sight. So far, all studies about radio polarization focused on the standard rotating vector model with the underlying assumption of a centred dipole. In this letter, we extend this model to the most general off-centred dipole configuration and give an exact closed analytic expression for the phase-resolved polarization angle. It is shown that contrary to the rotating vector model, for an off-centred dipole, the polarization angle also depends on the emission altitude. Although the fitting parameter space increases from two to six (position of the dipole, altitude and shift of the zero phase), statistical analysis should remain tractable. Observations revealing an evolution of the polarization angle with frequency would undeniably furnish a strong hint for the presence of a decentred magnetic dipole in neutron stars.

Accepted for publication in Monthly Notices of the Royal Astronomical Society Letters

References in corpus (3)

• Radiation from an off-centred rotating dipole in vacuum
• Stokes tomography of radio pulsar magnetospheres. I. Linear polarization
• Tackling Radio Polarization of Energetic Pulsars

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• The illusion of neutron star magnetic field estimates
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• A double dipole geometry for PSR~J0740+6620
• Multi-wavelength emission modelling of PSR~J0437$-$4715
• Evidence of the association of repeating fast-radio-burst sources with fast-spinning super-twisted magnetars
• Geometrical envelopes of fast radio bursts