Magnetic field dissipation in neutron star crusts: From magnetars to isolated neutron stars

By José A. Pons, U. Geppert. 2007

172 citations recorded by the source corpus.

Context. We study the non-linear evolution of magnetic fields in neutron star crusts with special attention to the influence of the Hall drift. Aims. Our goal is to understand the conditions for fast dissipation due to the Hall term in the induction equation. We study the interplay of Ohmic dissipation and Hall drift in order to find a timescale for the overall crustal field decay. Methods. We solve the Hall induction equation numerically by means of a hybrid method (spectral in angles but finite differences in the radial coordinate). The microphysical input consists of the most modern available crustal equation of state, composition, and electrical conductivities. Results. We present the first long-term simulations of the non-linear magnetic field evolution in realistic neutron star crusts with a stratified electron number density and temperature dependent conductivity. We show that Ohmic dissipation influenced by Hall drift takes place in neutron star crusts on a timescale of 10 6 years. When the initial magnetic field has magnetar strength, the fast Hall drift results in an initial rapid dissipation stage that lasts ∼10 4 years. The interplay of the Hall drift with the temporal variation and spatial gradient of conductivity tends to favor the displacement of toroidal fields toward the inner crust, where stable configurations can last for ∼ 10 6 years. We show that the thermally emitting, isolated neutron stars, such as the Magnificent Seven, are very likely descendants of neutron stars born as magnetars.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f935cc1c4dc4cb5a2fd6290b452617f2cfaefa7a

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Citations in the corpus

Three-dimensional simulations of neutrino-driven core-collapse supernovae from low-mass single and binary star progenitors (2018, background): “It is also noteworthy that the observed pulsars with high kicks and long birth spin periods tend to be old (&106 yr), and on these time scales magnetic field dissipation may become relevant (Pons et al. 2007; Pons & Geppert 2007), which could induce uncertainties in the inferred natal spin periods.”
Magneto-thermal evolution of neutron stars (2008, methodology): “There are two main differences from the induction equation employed in Pons & Geppert (2007): the relativistic factors are included and the magnetic diffusivity is not assumed to be spherically symmetric.”
A UNIFIED MODEL OF THE MAGNETAR AND RADIO PULSAR BURSTING PHENOMENOLOGY (2011, methodology): “OF NSS AND CRUSTAL FRACTURES We follow the evolution (in axial symmetry) of the magnetic field in a magnetar crust with the numerical code described in Pons & Geppert (2007).”
Unifying the observational diversity of isolated neutron stars via magneto-thermal evolution models. (2013, methodology): “In Pons & Geppert (2007), a spectral code follows the evolution of the magnetic field, including both the resistive and the Hall terms, but the temperature evolution was described by an isotropic, analytical cooling law.”
2D Cooling of Magnetized Neutron Stars (2007, background): “…t/τHall)−1 (19) while for late stages, whent ≥ τOhm B ≃ B0 exp(−t/τOhm) (20) This simple law reproduces qualitatively the results from more complex simulations (Pons & Geppert 2007) and facilitates the implementation of field decay in the cooling process of NSs for different Ohmic and Hall…”