Revisiting field burial by accretion onto neutron stars

TL;DR

This paper reviews recent advances in understanding how accreted matter can bury magnetic fields on neutron stars, potentially explaining the lower magnetic fields observed in millisecond pulsars.

Contribution

It provides new solutions to magneto-static equations with an improved plasma equation of state, shedding light on the magnetic field burial process in neutron stars.

Findings

Magnetic confinement solutions suggest effective field burial under accreted matter.

Improved plasma equation of state impacts the stability and extent of magnetic confinement.

Implications support the field burial mechanism as a reason for low magnetic fields in MSPs.

Abstract

The surface magnetic field strength of millisecond pulsars (MSPs) is found to be about 4 orders of magnitude lower than that of garden variety radio pulsars (with a spin of $\sim 0.5-5$ s and $B\sim 10^{12}$G). The exact mechanism of the apparent reduction of field strength in MSPs is still a subject of debate. One of the proposed mechanisms is burial of the surface magnetic field under matter accreted from a companion. In this article we review the recent work on magnetic confinement of accreted matter on neutron stars poles. We present the solutions of the magneto-static equations with a more accurate equation of state of the magnetically confined plasma and discuss its implications for the field burial mechanism.