Abstract
Black hole candidates sometimes show a transition between the high (or soft) state and the low (or hard) state. In the low state, low frequency time variations are much larger than the high state. A possible mechanism of the large-amplitude, sporadic time variabilities in the low-state is the magnetic energy release in low-β (β = P gas /P mag < 1) disks (Mineshige, Kusunose & Matsumoto 1995). It had been thought that low-β disks cannot exist because buoyant escape of magnetic flux due to the Parker instability may set the lower limit for β inside the disk. Shibata, Tajima & Matsumoto (1990), however, pointed out that in accretion disks, once a low-β disk is formed, it can stay in low-β state partly because the growth rate of the Parker instability decreases when β < 1. They suggested that magnetic accretion disks fall into two types; high-β disks and low-β disks.
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© 1998 Springer Science+Business Media Dordrecht
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Matsuzaki, T., Matsumoto, R., Tajima, T., Shibata, K. (1998). Three-Dimensional Local MHD Simulations of High States and Low States in Magnetic Accretion Disks. In: Koyama, K., Kitamoto, S., Itoh, M. (eds) The Hot Universe. International Astronomical Union / Union Astronomique Internationale, vol 188. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-4970-9_143
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DOI: https://doi.org/10.1007/978-94-011-4970-9_143
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