A new look at the origin of the 6.67\,hr period X-ray pulsar 1E~161348-5055

TL;DR

This paper proposes a novel model involving a magnetized fossil disk to explain the unusually long 6.67-hour pulsation period of the neutron star 1E 161348-5055, addressing previous difficulties in fall-back accretion scenarios.

Contribution

It introduces the concept of a magnetized fossil magnetic slab around the neutron star to account for its long spin period, a significant departure from traditional fall-back accretion models.

Findings

Magnetic slab can confine accreting material around the neutron star.

Surface magnetic field estimated at ~10^{12} G.

Magnetic slab mass > 10^{-7} M_sun explains the pulsar's properties.

Abstract

The point X-ray source 1E 161348-5055 is observed to display pulsations with the period 6.67 hr and |\dot{P}| \leq 1.6 x 10^{-9} s/s. It is associated with the supernova remnant RCW\,103 and is widely believed to be a ~2000 yr old neutron star. Observations give no evidence for the star to be a member of a binary system. Nevertheless, it resembles an accretion-powered pulsar with the magnetospheric radius ~3000 km and the mass-accretion rate ~ 10^{14} g/s. This situation could be described in terms of accretion from a (residual) fossil disk established from the material falling back towards the star after its birth. However, current fall-back accretion scenarios encounter major difficulties explaining an extremely long spin period of the young neutron star. We show that the problems can be avoided if the accreting material is magnetized. The star in this case is surrounded by a fossil magnetic slab in which the material is confined by the magnetic field of the accretion flow itself. We find that the surface magnetic field of the neutron star within this scenario is ~10^{12} G and that a presence of > 10^{-7} M_\sun magnetic slab would be sufficient to explain the origin and current state of the pulsar.