A short review of the pulsar magnetic inclination angles (II)

TL;DR

This paper reviews pulsar magnetic inclination angles, discusses their impact on pulsar properties, and uses observational data to constrain internal neutron star physics, including magnetic field structure and precession behavior.

Contribution

It applies a novel method to observational data to constrain internal neutron star parameters and suggests the internal magnetic field is likely toroidally dominated.

Findings

Constraints on precession cycle number $\xi$ for PSR J2013+3845

Internal magnetic field likely toroidally dominated

Implications for gravitational wave emission studies

Abstract

The pulsar magnetic inclination angle is a key parameter for pulsar physics. It influences the observable properties of pulsars, such as the pulse beam width, braking index, polarisation, and emission geometry. In this study, we give a brief overview of the current state of knowledge and research on this parameter and its implications for the internal physics of pulsars. We use the observed pulsar data of magnetic inclination angle and braking index to constrain the star's number of precession cycles, $\xi$, which reflects the interaction between superfluid neutrons and other particles inside a neutron star\,(NS). We apply the method proposed by Cheng et al. (2019) to analyse the data of PSR J2013+3845 and obtain the constraints for $\xi$ ranging from $2.393\times 10^{5}$ to $1.268\times10^{6}$. And further analysis suggests that the internal magnetic field structure of PSR J2013+3845 is likely dominated by toroidal component. This study may help us understand the process of internal viscous dissipation and the related evolution of the inclination angles of pulsars, and may have important implications for the study of continuous gravitational wave emissions from NS.