Magnetic field generated by r-modes in accreting quark stars

TL;DR

This paper investigates how r-mode instabilities in accreting quark stars can generate strong magnetic fields, influencing their spin evolution and transition to radio pulsars.

Contribution

It demonstrates that r-mode induced differential rotation can produce significant magnetic fields, altering the late-time evolution of accreting quark stars.

Findings

Magnetic fields are generated by r-modes in accreting quark stars.

Stars exit the millisecond pulsar region due to magnetic effects.

Maximum spin frequency is only slightly reduced by magnetic field generation.

Abstract

We show that the r-mode instability can generate strong toroidal fields in the core of accreting millisecond quark stars by inducing differential rotation. We follow the spin frequency evolution on a long time scale taking into account the magnetic damping rate in the evolution equations of r-modes. The maximum spin frequency of the star is only marginally smaller than in the absence of the magnetic field. The late-time evolution of the stars which enter the r-mode instability region is instead rather different if the generated magnetic fields are taken into account: they leave the millisecond pulsar region and they become radio pulsars.