CCOs and the hidden magnetic field scenario

TL;DR

This paper presents 2D simulations of magnetic field submergence and reemergence in neutron stars, supporting the hidden magnetic field scenario as an explanation for CCOs' low surface magnetic fields and their observational features.

Contribution

First 2D simulations of magnetic field burial and reemergence in neutron star crusts, validating the hidden magnetic field model for CCOs.

Findings

Magnetic field can be buried by post-supernova accretion of 1e-4-1e-3 solar masses.

Reemergence of the magnetic field occurs over 1-100 kyr after accretion stops.

Surface temperature anisotropy aligns with observations of CCOs.

Abstract

CCOs are X-ray sources lying close the center of supernova remnants, with inferred values of the surface magnetic fields significantly lower (less than about 1e11 G) than those of standard pulsars. In this paper, we revise the hidden magnetic field scenario, presenting the first 2D simulations of the submergence and reemergence of the magnetic field in the crust of a neutron star. A post-supernova accretion stage of about 1e-4-1e-3 solar masses over a vast region of the surface is required to bury the magnetic field into the inner crust. When accretion stops, the field reemerges on a typical timescale of 1-100 kyr, depending on the submergence conditions. After this stage, the surface magnetic field is restored close to its birth values. A possible observable consequence of the hidden magnetic field is the anisotropy of the surface temperature distribution, in agreement with observations of several of these sources. We conclude that the hidden magnetic field model is viable as alternative to the anti-magnetar scenario, and it could provide the missing link between CCOs and the other classes of isolated neutron stars.