Strong-field magnetohydrodynamics for neutron stars
Abstract
We present a formulation of magnetohydrodynamics which can be used to describe the evolution of strong magnetic fields in neutron star interiors. Our approach is based on viewing magnetohydrodynamics as a theory with a one-form global symmetry and developing an effective field theory for the hydrodynamic modes associated with this symmetry. In the regime where the local velocity and temperature variations can be neglected, we derive the most general constitutive relation consistent with symmetry constraints for the electric field in the presence of a strong magnetic field. This constitutive relation not only reproduces the phenomena of Ohmic decay, ambipolar diffusion, and Hall drift derived in a phenomenological model by Goldreich and Reisenegger, but also reveals new terms in the evolution of the magnetic field which cannot easily be seen from such microscopic models. This formulation gives predictions for novel diffusion behaviors of small perturbations around a constant background magnetic field, and for the two-point correlation functions among various components of the electric and magnetic fields.
Keywords
Cite
@article{arxiv.2207.01636,
title = {Strong-field magnetohydrodynamics for neutron stars},
author = {Shreya Vardhan and Sašo Grozdanov and Samuel Leutheusser and Hong Liu},
journal= {arXiv preprint arXiv:2207.01636},
year = {2024}
}
Comments
5+7 pages, 4 figures. Added in v2: comments on physical interpretation of the two new terms that appear in the constitutive relation for the magnetic field compared to earlier work of Goldreich and Reisenegger, and reference to arXiv:2408.12868 for the derivation of the effective action. Typos corrected. v3: Title changed to match published version