Magnetic Domains in Magnetar Matter as an Engine for Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars

TL;DR

This paper proposes that magnetic domain formation within magnetar matter could explain the origins of soft gamma-ray repeaters and anomalous X-ray pulsars, linking magnetic phase separation to observed high-energy phenomena.

Contribution

It introduces magnetic domain formation as a novel mechanism for SGRs and AXPs, identifying conditions for instability and energy release in magnetar interiors.

Findings

Magnetic domain instabilities occur in the outer crust and core of magnetars.

Energy released during domain formation matches observed SGR energies.

Parameter space for instability depends on density and magnetic field strength.

Abstract

Magnetars have been suggested as the most promising site for the origin of observed soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs). In this work we investigate the possibility that SGRs and AXPs might be observational evidence for a magnetic phase separation in magnetars. We study magnetic domain formation as a new mechanism for SGRs and AXPs in which magnetar-matter separates into two phases containing different flux densities. We identify the parameter space in matter density and magnetic field strength at which there is an instability for magnetic domain formation. We conclude that such instabilities will likely occur in the deep outer crust for the magnetic Baym, Pethick, and Sutherland (BPS) model and in the inner crust and core for magnetars described in relativistic Hartree theory. Moreover, we estimate that the energy released by the onset of this instability is comparable with the energy emitted by SGRs.