Finite-time Response of Dynamo Mean-field Effects in Magnetorotational Turbulence
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- Gressel_2022_ApJ_928_118
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Accretion disk turbulence along with its effect on large-scale magnetic fields plays an important role in understanding disk evolution in general, and the launching of astrophysical jets in particular. Motivated by enabling a comprehensive subgrid description for global long-term simulations of accretions disks, we aim to further characterize the transport coefficients emerging in local simulations of magnetorotational disk turbulence. For the current investigation, we leverage a time-dependent version of the test-field method, which is sensitive to the turbulent electromotive force (EMF) generated as a response to a set of pulsating background fields. We obtain Fourier spectra of the transport coefficients as a function of oscillation frequency. These are well approximated by a simple response function, describing a finite-time buildup of the EMF as a result of a time-variable mean magnetic field. For intermediate timescales (i.e., slightly above the orbital frequency), we observe a significant phase lag of the EMF compared to the causing field. Augmented with our previous result on a nonlocal closure relation in space, and incorporated into a suitable mean-field description that we briefly sketch out here, the new framework will allow us to drop the restrictive assumption of scale separation.
Original language | English |
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Article number | 118 |
Journal | Astrophysical Journal |
Volume | 928 |
Issue number | 2 |
Number of pages | 7 |
ISSN | 0004-637X |
DOIs | |
Publication status | Published - 1 Apr 2022 |
- ROTATING MAGNETOCONVECTION, SHEARING BOX, IMPLEMENTATION, SIMULATIONS, INSTABILITY, SATURATION, PATTERNS, I.
Research areas
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