Progenitors of Magnetars and Hyperaccreting Magnetized Disks

TL;DR

This paper explores how magnetars can form from core collapse or neutron star mergers, emphasizing the role of hyperaccreting disks in magnetic field inheritance and their impact on subsequent accretion and X-ray luminosity.

Contribution

It introduces a new model where hyperaccreting disks magnify magnetic fields, leading to magnetar formation and influencing their X-ray emission properties.

Findings

Magnetars can form via core collapse or neutron star mergers with magnetic field inheritance.

Decay of toroidal magnetic fields sustains persistent X-ray luminosity in SGRs and AXPs.

Poloidal field decay alone is insufficient for X-ray luminosity.

Abstract

We propose that a magnetar could be formed during the core collapse of massive stars or coalescence of two normal neutron stars, through collecting and inheriting the magnetic fields magnified by hyperaccreting disk. After the magnetar is born, its dipole magnetic fields in turn have a major influence on the following accretion. The decay of its toroidal field can fuel the persistent X-ray luminosity of either an SGR or AXP; however the decay of only the poloidal field is insufficient to do so.