Modified viscosity in accretion disks

Mikołaj Grzędzielski, Agnieszka Janiuk, Bożena Czerny and Qingwen Wu

Black holes surrounded by accretion disks are present in the Universe in different scales of masses, from microquasars, up to Active Galactic Nuclei. The basic theory of a geometrically thin, stationary accretion is based on α prescription which assumes the proportionality between non-diagonal stress tensor term and the total pressure. Domination of thermal pressure leads to thermal instability, which results in limit-cycle oscillations in sources like GRS1915+105 and IGR J17091-3624. In our work, we examined large grid of accretion disk models with generalized description of viscosity. In general, the parameter range of the presence of limit-cycle oscillations and their amplitude can be reduced by magnetic field. We model its influence by extending the global code GLADIS to include the μ magnetic viscosity parameter. We used this modelling to determine the mass of the intermediate mass black hole of HLX-1 and its accretion rate from the observed flares, detected by the Swift X-ray satellite. Furthermore, we extended our model by including atomic processes. It partially reduced the instability of the disk in case of Active Galactic Nuclei.

Proceedings of the Polish Astronomical Society, vol. 7, 291-297 (2018)

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