MHD instabilities in accretion mounds - II. 3D simulations

TL;DR

This paper uses 3D MHD simulations to study pressure-driven instabilities in neutron star accretion mounds, revealing how mound mass influences instability development and potential observable effects.

Contribution

It provides the first detailed 3D simulation analysis of pressure-driven instabilities in accretion mounds, linking mound mass to instability growth and observational signatures.

Findings

Instabilities form finger-like channels at the mound periphery for masses beyond a threshold.

Hollow interior ring-like mounds also exhibit inner edge instabilities.

Mound mass affects the growth rate of instabilities.

Abstract

We investigate the onset of pressure driven toroidal mode instabilities in accretion mounds on neutron stars by 3D MHD simulations using the PLUTO MHD code. Our results confirm that for mounds beyond a threshold mass, instabilities form finger like channels at the periphery, resulting in mass loss from the magnetically confined mound. Ring like mounds with hollow interior show the instabilities at the inner edge as well. We perform the simulations for mounds of different sizes to investigate the effect of the mound mass on the growth rate of the instabilities. We also investigate the effect of such instabilities on observables such as cyclotron resonant scattering features and timing properties of such systems.