From proto-neutron star dynamo to low-field magnetars
Abstract
Low-field magnetars have dipolar magnetic fields that are 10-100 times weaker than the threshold, G, used to define classical magnetars, yet they produce similar X-ray bursts and outbursts. Using the first direct numerical simulations of magneto-thermal evolution starting from a dynamo-generated magnetic field, we show that the low-field magnetars can be produced as a result of a Tayler--Spruit dynamo inside the proto-neutron star. We find that these simulations naturally explain key characteristics of low-field magnetars: (1) weak ( G) dipolar magnetic fields, (2) strong small-scale fields, and (3) magnetically induced crustal failures producing X-ray bursts. These findings suggest two distinct formation channels for classical and low-field magnetars, potentially linked to different dynamo mechanisms.
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@article{arxiv.2501.04768,
title = {From proto-neutron star dynamo to low-field magnetars},
author = {Andrei Igoshev and Paul Barrère and Raphaël Raynaud and Jérome Guilet and Toby Wood and Rainer Hollerbach},
journal= {arXiv preprint arXiv:2501.04768},
year = {2025}
}
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