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Magnetoseismology of accretion disks: towards the full spectrum for turbulent disks.

Context: Accretion disks are ubiquitous in the Universe, occurring whenever gravitational collapse forms a disk of material around e.g. a protostar or a black hole. Understanding the evolution of young stars and Active Galactic Nuclei requires knowledge of the process behind accretion onto these central objects. Turbulence proves to be essential to explaining the observed high accretion rates. Aim: We aim to investigate the full spectrum of waves and instabilities of the magnetohydrodynamics fluid equations for various realistic models of accretion disks. This will reveal a plethora of instabilities that are responsible for accretion disk turbulence, besides the already well-established Magneto-Rotational Instability that is currently the only named mechanism in literature. Methods: Analytic and numerical studies of the linear spectrum for increasingly complex disk equilibria will be made, using the spectral code Legolas and the code pair FINESSE-PHOENIX. These results will then be compared to fully nonlinear simulations of disks with MPI-AMRVAC. Results: We will extend the theoretical knowledge on recently discovered instabilities in accretion disks and uncover entirely new instabilities by considering additional physical effects. By comparing the linear results to nonlinear simulations, we then will quantify for the first time the influence of each distinct instability on the different phases of the turbulent nonlinear evolution of accretion disks.

Date:15 Sep 2021 →  Today
Keywords:MHD, Plasma physics
Disciplines:Space plasma physics and solar physics
Project type:PhD project