Department of Physics, Graduate School of Science, Chiba University
National Astronomical Observatory
Graduate School of Science and Technology, Chiba University
出版者
宇宙航空研究開発機構
出版者（英）
Japan Aerospace Exploration Agency (JAXA)
雑誌名
宇宙航空研究開発機構特別資料
雑誌名(英)
JAXA Special Publication: Astrophysics with All-Sky X-Ray observations: 3rd International MAXI Workshop
巻
JAXA-SP-08-014E
ページ
126 - 131
発行年
2009-02-27
会議概要（会議名, 開催地, 会期, 主催者等）（英）
Astrophysics with All-Sky X-Ray observations: 3rd International MAXI Workshop (RIKEN, 10-12 June 2008)
抄録（英）
Global three-dimensional magnetohydrodynamic simulations of black hole accretion disks enable us to study the time variabilities of black hole accretion disks without introducing the phenomenological alpha viscosity. Numerical simulations including optically thin radiative cooling revealed that when the disk luminosity exceeds 0.01 L(sub Edd), where L(sub Edd) is the Eddington luminosity, cooling instability taking place in the low/hard state disk creates a magnetically supported, optically thin luminous disk (high/hard state disk) whose X-ray luminosity exceeds 0.1 L(sub Edd) when the accretion rate continues to increase. We found that when the outer region of the disk (r > 20 r(sub s) , where r(sub s) is the Schwarzschild radius) undergoes this transition, an inner torus is formed in r < 10 r(sub s) . The inner torus produces low-frequency quasi-periodic oscillations (QPOs) and high-frequency QPOs whose frequency are 1 - 10 Hz, and ca. 100 Hz, respectively for stellar mass black holes, and 10(exp -6) - 10(exp -5) Hz, and ca. 10(exp -4) Hz, respectively for Seyfert galaxies with black hole mass 10(exp 7) solar mass. When the magnetic energy stored in the disk is released, the disk completes the transition to an optically thick, high/soft state. Monitoring observations by MAXI will detect these transitions in stellar mass black holes and QPOs in AGNs.
内容記述（英）
Physical characteristics: Original contains color illustrations
Variability science in accretion disk theory
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