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Ab initio simulations of accretion disc boundary layers

Philip J. Armitage
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Abstract

I discuss the results of simplified three dimensional magnetohydrodynamic simulations of the boundary layer between a disc and a non-rotating, unmagnetized star. Strong magnetic fields, possibly approaching equipartition with the thermal energy, occur in the boundary layer due to the shearing of disc-generated fields. The mean boundary layer magnetic field, which is highly variable on an orbital timescale, is estimated to exceed 50 kG for a CV with an accretion rate of 10^(-9) solar masses per year. However, these fields do not drive efficient angular momentum transport within the boundary layer. As a consequence the radial velocity in the boundary layer is low, and the density high.

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Philip J. Armitage. 2001-10-10. Ab initio simulations of accretion disc boundary layers. https://arxiv.org/abs/astro-ph/0110250

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