X-ray study of state transitions of black hole binaries

2016 Fiscal Year Final Research Report

• Project/Area Number: 24540237
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Shibaura Institute of Technology
• Principal Investigator: Kubota Aya 芝浦工業大学, システム理工学部, 准教授 (00391938)
• Research Collaborator: Done Chris
• Project Period (FY): 2012-04-01 – 2017-03-31
• Keywords: X線 / ブラックホール / 降着流 / 状態遷移 / すざく衛星 / very high state

Outline of Final Research Achievements

The two best known black hole binary states are the low/hard and high/soft states. The low/hard state is dominated by hard Comptonised emission from a hot, optically thin flow whereas the high/soft state is instead dominated by soft, blackbody emission from a cool, optically thick disk. To understand what makes the transition is the key issue to understand important parameters which determine the emission efficiency. Especially the very high state (VHS) is the key to understand the transition since it is the intermediate state between the high state and the low state. We developed a physical model for the accretion flow structure in the VHS, in which both thermal and non-thermal electrons are taken into account. Then we fit good VHS data observed with Suzaku, and found that the disk is truncated in the VHS and the corona can be understand with fully non-thermal electrons.

Free Research Field

X線天文学　ブラックホール観測