SGRs and AXPs as massive fast rotating highly magnetized white dwarfs: the case of SGR 0418+5729

TL;DR

This paper models SGR 0418+5729 as a massive, fast-rotating, highly magnetized white dwarf, providing bounds on its physical parameters and predicting its spin-down rate and magnetic field characteristics.

Contribution

It introduces a white dwarf model for SGR 0418+5729, deriving bounds on its properties and improving predictions of its spin-down rate based on relativistic rotating configurations.

Findings

Bounds on mass, radius, and magnetic field of SGR 0418+5729

Predicted lower limit of the spin-down rate

Computed electron cyclotron frequencies for surface magnetic fields

Abstract

We describe one of the so-called low magnetic field magnetars SGR 0418+5729, as a massive fast rotating highly magnetized white dwarf following Malheiro et. al. 2012. We give bounds for the mass, radius, moment of inertia, and magnetic field for these sources, by requesting the stability of realistic general relativistic uniformly rotating configurations. Based on these parameters, we improve the theoretical prediction of the lower limit of the spin-down rate of SGR 0418+5729. In addition, we compute the electron cyclotron frequencies corresponding to the predicted surface magnetic fields.