The stress–pressure lag in MRI turbulence and its implications for thermal instability in accretion discs
| Autor: | Loren E. Held, Henrik N. Latter |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Physics Shearing (physics) Accretion (meteorology) Turbulence Oscillation Lag Fluid Dynamics (physics.flu-dyn) FOS: Physical sciences Astronomy and Astrophysics Physics - Fluid Dynamics Mechanics Stress (mechanics) Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Thermal Astrophysics::Earth and Planetary Astrophysics Magnetohydrodynamic drive Astrophysics - High Energy Astrophysical Phenomena Solar and Stellar Astrophysics (astro-ph.SR) |
| Zdroj: | Monthly Notices of the Royal Astronomical Society |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stab3398 |
| Popis: | The classical alpha-disc model assumes that the turbulent stress scales linearly with -- and responds instantaneously to -- the pressure. It is likely, however, that the stress possesses a non-negligible relaxation time and will lag behind the pressure on some timescale. To measure the size of this lag we carry out unstratified 3D magnetohydrodynamic shearing box simulations with zero-net-magnetic-flux using the finite-volume code PLUTO. We impose thermal oscillations of varying periods via a cooling term, which in turn drives oscillations in the turbulent stress. Our simulations reveal that the stress oscillations lag behind the pressure by $\sim 5$ orbits in cases where the oscillation period is several tens of orbits or more. We discuss the implication of our results for thermal and viscous overstability in discs around compact objects. Accepted for publication in MNRAS (8 pages, 7 figures) |
| Databáze: | OpenAIRE |
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