Magnetic fields in late-stage proto-neutron stars

Lander, S. K., Haensel, P., Haskell, B., Zdunik, J. L. and Fortin, M. (2021) Magnetic fields in late-stage proto-neutron stars. Monthly Notices of the Royal Astronomical Society, 503 (1). 875–895. ISSN 0035-8711

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Abstract

We explore the thermal and magnetic field structure of a late-stage proto-neutron star (proto-NS). We find the dominant contribution to the entropy in different regions of the star, from which we build a simplified equation of state (EOS) for the hot neutron star (NS). With this, we numerically solve the stellar equilibrium equations to find a range of models, including magnetic fields and rotation up to Keplerian velocity. We approximate the EOS as a barotrope, and discuss the validity of this assumption. For fixed magnetic field strength, the induced ellipticity increases with temperature; we give quantitative formulae for this. The Keplerian velocity is considerably lower for hotter stars, which may set a de facto maximum rotation rate for non-recycled NSs well below 1 kHz. Magnetic fields stronger than around 1014 G have qualitatively similar equilibrium states in both hot and cold NSs, with large-scale simple structure and the poloidal field component dominating over the toroidal one; we argue this result may be universal. We show that truncating magnetic field solutions at low multipoles leads to serious inaccuracies, especially for models with rapid rotation or a strong toroidal-field component.

Item Type: Article
Uncontrolled Keywords: stars: evolution,stars: interiors,stars: magnetic fields,stars: neutron,stars: rotation,astronomy and astrophysics,space and planetary science ,/dk/atira/pure/subjectarea/asjc/3100/3103
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Depositing User: LivePure Connector
Date Deposited: 06 May 2021 00:03
Last Modified: 12 Jun 2021 12:12
URI: https://ueaeprints.uea.ac.uk/id/eprint/79928
DOI: 10.1093/mnras/stab460

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