On the Magnetic Field of Pulsars with Realistic Neutron Stars Configurations

TL;DR

This paper models the magnetic fields of pulsars using realistic neutron star configurations within general relativity, revealing significant differences from traditional estimates and clarifying the nature of high-magnetic field pulsars.

Contribution

It introduces a neutron star model based on coupled Einstein-Maxwell-Thomas-Fermi equations with realistic parameters, improving magnetic field estimates for pulsars.

Findings

Realistic neutron star parameters lead to different magnetic field estimates.

General relativistic models show lower magnetic fields than Newtonian models.

High-magnetic field pulsars can be explained as rotationally powered, with fields below quantum critical levels.

Abstract

We have recently developed a neutron star model fulfilling global and not local charge neutrality, both in the static and in the uniformly rotating cases. The model is described by the coupled Einstein-Maxwell-Thomas- Fermi (EMTF) equations, in which all fundamental interactions are accounted for in the framework of general relativity and relativistic mean field theory. Uniform rotation is introduced following the Hartle's formalism. We show that the use of realistic parameters of rotating neutron stars obtained from numerical integration of the self-consistent axisymmetric general relativistic equations of equilibrium leads to values of the magnetic field and radiation efficiency of pulsars very different from estimates based on fiducial parameters assuming a neutron star mass, M = 1.4 Msun, radius R = 10 km, and moment of inertia, I = 10^45 g cm^2. In addition, we compare and contrast the magnetic field inferred from the traditional Newtonian rotating magnetic dipole model with respect to the one obtained from its general relativistic analog which takes into due account the effect of the finite size of the source. We apply these considerations to the specific high-magnetic field pulsars class and show that, indeed, all these sources can be described as canonical pulsars driven by the rotational energy of the neutron star, and with magnetic fields lower than the quantum critical field for any value of the neutron star mass.