English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The magnetorotational instability (MRI) can be a powerful mechanismamplifying the magnetic field in core-collapse supernovae. Whether initiallyweak magnetic fields can be amplified by this instability to dynamicallyrelevant strengths is still a matter of debate. One of the main uncertaintiesconcerns the process that terminates the growth of the instability. Parasiticinstabilities of both Kelvin-Helmholtz and tearing-mode type have beensuggested to play a crucial role in this process, disrupting MRI channel flowsand quenching magnetic field amplification. We perform two-dimensional andthree-dimensional sheering-disc simulations of a differentially rotatingprotoneutron star layer in non-ideal magnetohydrodynamics with unprecedentedhigh numerical accuracy, finding that Kelvin-Helmholtz parasitic modes dominatetearing modes in the regime of large hydrodynamic and magnetic Reynoldsnumbers, as encountered close to the surface of protoneutron stars. They alsodetermine the maximum magnetic field stress achievable during the exponentialgrowth of the MRI. Our results are consistent with the theory of parasiticinstabilities based on a local stability analysis. To simulate theKelvin-Helmholtz instabilities properly, a very high numerical resolution isnecessary. Using ninth-order spatial reconstruction schemes, we find that atleast eight grid zones per MRI channel are necessary to simulate the growthphase of the MRI and reach an accuracy of ~10 per cent in the growth rate,while more than ~60 zones per channel are required to achieve convergentresults for the value of the magnetic stress at MRI termination.

Termination of the magnetorotational instability via parasitic instabilities in core-collapse supernovae