2018 Fiscal Year Annual Research Report
The nexus between kinematic complexity and black holes in star clusters
| Project/Area Number |
18F18787
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| Research Institution | The University of Tokyo |
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Principal Investigator |
藤井 通子 東京大学, 大学院理学系研究科(理学部), 准教授 (90722330)
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| Co-Investigator(Kenkyū-buntansha) |
VARRI ANNA LISA 東京大学, 理学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2018-11-09 – 2021-03-31
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| Keywords | star clusters / angular momentum / kinematic complexity / N-body simulations |
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| Outline of Annual Research Achievements |
The theoretical investigation of the role of 'kinematic complexity' in the dynamical evolution of collisional stellar systems has been progressing appropriately. During the fellowship tenure in FY2018 (30 November 2018 - 31 March 2019) one article on this topic has been submitted to the peer-reviewed journal MNRAS and two additional papers will be submitted to the same journal shortly. These manuscripts have been prepared in collaboration with researchers at the University of Edinburgh, as indicated in the original fellowship proposal. For this reason, one visit to Edinburgh (in Janurary 2019) has been conducted. In addition to the regular group meeting seminars, I have also presented two colloquia at the University of Tokyo (UTokyo), within the Dept. of Astronomy and Dept. of Physics, respectively. Both colloquia have been well received and enabled me to establish new collaborative links within UTokyo. Finally, among other activities, I have participated in two conferences (a Kavli IPMU and UTokyo, respectively) and in the one-day event 'Nobel Prize Dialogue 2019' organized by JSPS in Yokohama.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The theoretical investigation of the role of 'kinematic complexity' in the dynamical evolution of collisional stellar systems has been progressing appropriately (see Point 1 for further details).
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| Strategy for Future Research Activity |
The existence of intermediate-mass black holes (IMBHs) is a topical problem in modern astrophysics. However, possible detections remain so far inconclusive. In FY2019 we will continue to make progress towards addressing the following key questions:(1) What is the physical origin of the nexus between kinematic complexity and black holes in dense stellar systems?(2) Do globular clusters host intermediate-mass black holes?
according to the following research plan:
Equilibrium - We will construct novel rotating, anisotropic, models, defined as a distribution function in phase space which includes a central intermediate-mass black hole (IMBH). We will then develop a Bayesian fitting method to directly compare new discrete astrometric data from Hubble Space Telescope and Gaia to a phase space distribution function. We will apply the new models to key Galactic clusters identified as promising candidates for hosting an IMBH.
Evolution - Starting from the equilibria above, we will explore, with N-body simulations, the long-term evolution of multi-mass rotating systems with an IMBH, with attention to the transport of angular momentum. We will study the interactions between the IMBH and the stellar-mass BHs forming in such N-body models. We will estimate the rate of IMBH-BH mergers and their detectability with LIGO-Virgo, KAGRA, DECIGO, and LISA. Such a class of gravitational waves, together with the new dynamical models, will offer a powerful IMBH diagnostics.
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| Remarks |
When the articles will be accepted for publication, a summary of the results will be presented in my professional webpage:
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