MRI-driven dynamo at high Pm numbers
arXiv:2501.05393 · doi:10.1051/0004-6361/202553714
Abstract
To power gamma-ray bursts and other high-energy events, large-scale magnetic fields are required to extract rotational energy from compact objects such as black holes and neutron stars. The magnetorotational instability (MRI) is a key mechanism for angular momentum transport and large-scale magnetic field amplification. Recent work has begun to address the regime of high magnetic Prandtl number , the ratio of viscosity to resistivity, in which angular momentum and magnetic energy increase with . This regime reveals unique dynamics of small-scale turbulence in disk mid-planes and buoyancy instabilities in the atmosphere. This study aims to build on these findings, focusing on the MRI-driven dynamo in stratified simulations to understand magnetic field generation in the high- regime. We analyze data taken from stratified shearing box simulations both in the regime of magnetic Prandtl number of order unity, and also in the high regime employing new techniques to compute the dynamo coefficients. We find that the mean-magnetic field evolution can be described by an dynamo, even in the high-Pm regime. The mean magnetic field as well as the dynamo coefficients increase with Pm. This leads to a shorter dynamo period and a faster growth rate. We also find that the off-diagonal coefficients have an impact on the propagation of the magnetic field in the dynamo region. Overall, the magnetic field amplification found in global simulations should be increased by at least a factor of , which could lead to more powerful jets and stronger winds from astrophysical disks in the high-Pm regime.
9 pages, 6 figures, submitted to A&A
References in corpus (24)
- Multi-messenger Observations of a Binary Neutron Star Merger
- Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
- An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
- INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational Wave Event GW170817
- Magnetorotationally driven Supernovae as the origin of early galaxy -process elements?
- Short Duration Gamma-Ray Bursts with Extended Emission from Proto-Magnetar Spin-Down
- Magnetorotational Core-Collapse Supernovae in Three Dimensions
- MHD simulations of the magnetorotational instability in a shearing box with zero net flux. II. The effect of transport coefficients
- Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
- Angular Momentum Transport in Accretion Disks: Scaling Laws in MRI-driven Turbulence
- On the Magnetic Prandtl Number Behavior of Accretion Disks
- Post-merger Mass Ejection of Low-mass Binary Neutron Stars
- End-to-end kilonova models of neutron-star mergers with delayed black-hole formation
- Long-term evolution of neutron-star merger remnants in general relativistic resistive-magnetohydrodynamics with a mean-field dynamo term
- Neutrino viscosity and drag: impact on the magnetorotational instability in protoneutron stars
- On the jet-ejecta interaction in 3D GRMHD simulations of binary neutron star merger aftermath
- Dissipative effects on the sustainment of a magnetorotational dynamo in Keplerian shear flow
- Magnetorotational dynamo chimeras. The missing link to turbulent accretion disk dynamo models?
- Impact of a mean field dynamo on neutron star mergers leading to magnetar remnants
- Microphysical dissipation, turbulence and magnetic fields in hyper-accreting discs
- Finite-time response of dynamo mean-field effects in magnetorotational turbulence
- MRI turbulence in vertically stratified accretion discs at large magnetic Prandtl numbers
- Iterative removal of sources to model the turbulent electromotive force
- Shedding light on the MRI driven dynamo in a stratified shearing box