# Estimating magnetar radii with an empirical meta-model

## TL;DR

This paper investigates how strong magnetic fields in magnetars influence their crust-core transition and size, using an extended meta-model and numerical calculations to understand astrophysical phenomena.

## Contribution

It extends a meta-model to include magnetic field effects on neutron star matter, providing new insights into crust-core properties under strong magnetic conditions.

## Key findings

- Magnetic fields significantly alter crust-core transition properties.
- Quantitative differences found between simplified and full numerical models.
- Results impact interpretation of magnetar phenomena such as glitches and bursts.

## Abstract

The presence of strong magnetic fields in neutron stars, such as in magnetars, may significantly affect their crust-core transition properties and the crust size. This knowledge is crucial in the correct interpretation of astrophysical phenomena involving magnetars, such as glitches in observed rotation frequencies, cooling, bursts and possibly tidal polarizabilities. A recently developed meta-modelling technique allows exploring the model dependence of density functional theory equation of state calculations. In this work, we extend this meta-model to investigate the effect of strong magnetic fields on spinodal instabilities of neutron star matter and the associated crust-core properties. Both Tolman-Oppenheimer-Volkov and a full self-consistent numerical calculations are performed for the neutron star structure, the results being quantitatively different for strong magnetic fields.