Probing the surface magnetic field structure in RX J1856.5-3754

TL;DR

This study investigates the surface magnetic field structure of RX J1856.5-3754 to test predictions of neutron star magnetic field evolution models, specifically the Hall attractor phase, using X-ray spectral data.

Contribution

It provides the first observational test of the Hall attractor model in a nearby neutron star through spectral analysis.

Findings

RX J1856.5-3754 may be closer to the Hall attractor phase than other neutron stars.

Surface emission properties predicted by the Hall attractor model conflict with observed spectral data.

Abstract

The evolution of magnetic field in isolated neutron stars is one of the most important ingredients in the attempt to build a unified description of these objects. A prediction of field evolution models is the existence of an equilibrium configuration, in which the Hall cascade vanishes. Recent calculations have explored the field structure in this stage, called the Hall attractor. We use X-ray data of near-by, cooling neutron stars to probe this prediction, as these sources are surmised to be close to or at Hall attractor phase. We show that the source RX J1856.5-3754 might be closer to the attractor than other sources of its class. Our modelling indicates that the properties of surface thermal emission, assuming that the star is in the Hall attractor, are in contradiction with the spectral data of RX J1856.5-3754.