The magnetospheric activity of bare strange quark stars

TL;DR

This paper investigates the magnetospheric activity of bare strange quark stars, demonstrating that they can sustain vacuum gaps due to strong binding energies, which may help distinguish them from normal neutron stars.

Contribution

It provides a detailed analysis of the electric potential barriers in bare strange quark stars, showing they can maintain vacuum gaps unlike normal neutron stars.

Findings

Electrons are prevented from streaming into the magnetosphere unless the pulsar's electric potential is very low.

Both positive and negative particles are strongly bound on the surface of a BSS, enabling vacuum gap formation.

Multi-accelerator regions can exist in the magnetosphere of a BSS.

Abstract

In Ruderman & Sutherland (RS75) model, the normal neutron stars as pulsars bear a severe problem, namely the binding energy problem that both ions (e.g., ${}_{26}^{56}$Fe) and electrons on normal neutron star surface can be pulled out freely by the unipolar generator induced electric field so that sparking on polar cap can hardly occur. {\bf This problem could be solved within the Partially Screened Gap (PSG) model in the regime of neutron stars}. However, in this paper we extensively study this problem in a bare strange quark star (BSS) model. We find that the huge potential barrier built by the electric field in the vacuum gap above polar cap could usually prevent electrons from streaming into the magnetosphere unless the electric potential of a pulsar is sufficiently lower than that at infinite interstellar medium. Other processes, such as the diffusion and thermionic emission of electrons have also been included here. Our conclusions are as follows: both positive and negative particles on a BSS's surface would be bound strongly enough to form a vacuum gap above its polar cap as long as the BSS is not charged (or not highly negative charged), and multi-accelerators could occur in a BSS's magnetosphere. Our results would be helpful to distinguish normal neutron stars and bare quark stars through pulsar's magnetospheric activities.