Magnetic field distribution in magnetars

Debarati Chatterjee , Jerome Novak (1) , Micaela Oertel (1)

1 LUTH (UMR_8102) - Laboratoire Univers et Théories

Using an axisymmetric numerical code, we perform an extensive study of the magnetic field configurations in non-rotating neutron stars, varying the mass, magnetic field strength and the equation of state. We find that the monopolar (spherically symmetric) part of the norm of the magnetic field can be described by a single profile, that we fit by a simple eighth-order polynomial, as a function of the star's radius. This new generic profile applies remarkably well to all magnetized neutron star configurations built on hadronic equations of state. We then apply this profile to build magnetized neutron stars in spherical symmetry, using a modified Tolman-Oppenheimer-Volkov system of equations. This new formalism satisfactorily reproduces the correct behavior of the neutron star total mass with increasing magnetic field. Our " universal " magnetic field profile is intended to serve as a tool for nuclear physicists to obtain estimates of magnetic field inside neutron stars, as a function of radial depth, in order to deduce its influence on composition and related properties. It possesses the advantage of being based on magnetic field distributions from realistic self-consistent computations, which are solutions of Maxwell's equations.

Mots clés: 2660Dd; 2660-c; numbers: 9760Jd; 0425D-; 0440Dg

Domaines: Physique Nucléaire Théorique [nucl-th]; Phénomènes cosmiques de haute energie [astro-ph.HE]; Relativité Générale et Cosmologie Quantique [gr-qc]

Debarati Chatterjee, Jerome Novak, Micaela Oertel. Magnetic field distribution in magnetars. 2018. ⟨hal-01853671v1⟩