Subgrid modelling of MRI-driven turbulence in differentially rotating neutron stars

Fuente: arXiv
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Auteurs principaux: Miravet-Tenés, Miquel, Obergaulinger, Martin, Cerdá-Durán, Pablo, Font, José A., Ruiz, Milton
Format: Preprint
Publié: 2025
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author Miravet-Tenés, Miquel
Obergaulinger, Martin
Cerdá-Durán, Pablo
Font, José A.
Ruiz, Milton
author_facet Miravet-Tenés, Miquel
Obergaulinger, Martin
Cerdá-Durán, Pablo
Font, José A.
Ruiz, Milton
contents Following a binary neutron star (BNS) merger, the transient remnant is often a fast-spinning, differentially rotating, magnetised hypermassive neutron star (HMNS). This object is prone to the magnetorotational instability (MRI) which drives magnetohydrodynamic turbulence that significantly influences the HMNS global dynamics. A key consequence of turbulence is the outward transport of angular momentum which impacts the remnant's stability and lifetime. Most numerical simulations of BNS mergers are unable to resolve the MRI due to its inherently small wavelength. To overcome this limitation, subgrid models have been proposed to capture the effects of unresolved small-scale physics in terms of large-scale quantities. We present the first implementation of our MHD-Instability-Induced Turbulence (MInIT) model in global Newtonian simulations of MRI-sensitive, differentially rotating, magnetised neutron stars. Here, we show that by adding the corresponding turbulent stress tensors to the momentum equation, MInIT successfully reproduces the angular momentum transport in neutron stars driven by small-scale turbulence.
format Preprint
id arxiv_https___arxiv_org_abs_2509_07081
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Subgrid modelling of MRI-driven turbulence in differentially rotating neutron stars
Miravet-Tenés, Miquel
Obergaulinger, Martin
Cerdá-Durán, Pablo
Font, José A.
Ruiz, Milton
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Following a binary neutron star (BNS) merger, the transient remnant is often a fast-spinning, differentially rotating, magnetised hypermassive neutron star (HMNS). This object is prone to the magnetorotational instability (MRI) which drives magnetohydrodynamic turbulence that significantly influences the HMNS global dynamics. A key consequence of turbulence is the outward transport of angular momentum which impacts the remnant's stability and lifetime. Most numerical simulations of BNS mergers are unable to resolve the MRI due to its inherently small wavelength. To overcome this limitation, subgrid models have been proposed to capture the effects of unresolved small-scale physics in terms of large-scale quantities. We present the first implementation of our MHD-Instability-Induced Turbulence (MInIT) model in global Newtonian simulations of MRI-sensitive, differentially rotating, magnetised neutron stars. Here, we show that by adding the corresponding turbulent stress tensors to the momentum equation, MInIT successfully reproduces the angular momentum transport in neutron stars driven by small-scale turbulence.
title Subgrid modelling of MRI-driven turbulence in differentially rotating neutron stars
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2509.07081