Precession of triaxially deformed neutron stars

TL;DR

This paper models the precession of triaxially deformed neutron stars, deriving analytical solutions for their motion and gravitational waveforms, and explores electromagnetic pulse modulations considering vacuum torque effects.

Contribution

It provides a new analytical framework for describing neutron star precession and gravitational waveforms, extending previous models with a more convenient parameterization and torque considerations.

Findings

Analytical solutions for angular velocities and Euler angles of precessing NSs.

Waveforms for gravitational waves from freely precessing triaxial NSs.

Modeling of pulsar timing residuals and pulse modulations with a simple cone model.

Abstract

A deformed neutron star (NS) will precess if the instantaneous spin axis and the angular momentum are not aligned. Such a precession can produce continuous gravitational waves (GWs) and modulate electromagnetic pulse signals of pulsars. In this contribution we extend our previous work in a more convenient parameterization. We treat NSs as rigid triaxial bodies and give analytical solutions for angular velocities and Euler angles. We summarize the general GW waveforms from freely precessing triaxial NSs and use Taylor expansions to obtain waveforms with a small wobble angle. For pulsar signals, we adopt a simple cone model to study the timing residuals and pulse profile modulations. In reality, the electromagnetic torque acts on pulsars and affects the precession behavior. Thereof, as an additional extension to our previous work, we consider a vacuum torque and display an illustrative example for the residuals of body-frame angular velocities. Detailed investigations concerning continuous GWs and modulated pulsar signals from forced precession of triaixal NSs will be given in future studies.