Speaker
Description
The long-term evolution of neutron stars' strong internal magnetic fields requires advanced numerical modeling. Observations suggest a highly non-uniform magnetic structure, underscoring the need for three-dimensional simulations. In this talk, I will introduce MATINS, a novel three-dimensional numerical code based on a finite-volume scheme, specifically designed to simulate magneto-thermal evolution in neutron star crusts. I will present results from the first fully coupled three-dimensional magneto-thermal simulations incorporating realistic background structures and microphysics. Our simulations, initialized with intricate field configurations from proto-neutron star dynamo models, show that the surface dipolar component remains weak over time. This raises fundamental questions about the mechanisms driving the large-scale magnetic fields observed in neutron stars. To explore this, we examine the inverse cascade phenomenon, analyzing the influence of magnetic helicity, crustal geometry, and boundary conditions on field evolution. Additionally, we investigate the chiral magnetic instability, a microphysical process that can amplify large-scale magnetic fields in the crust. Driven by deviations from chemical equilibrium caused by spin-down evolution, this instability naturally generates magnetic helicity and facilitates the formation of strong toroidal fields, offering an alternative to classical dynamo models. These findings provide fresh insight into the origin and dynamics of neutron star magnetic fields, particularly in magnetars.
