| 研究実績の概要 |
The first gravitational wave event observed by LIGO-Virgo-Kagra has opened a new observable window on the universe. However, the origin of gravitational wave events is still unknown. We investigated several formation pathways for gravitational wave formation events, which involve few-body interactions and binary stellar evolution processes. In Trani et al. 2022a, we studied how hierarchical triple stars formed in star cluster can produce gravitational wave events from black hole binaries, black hole - neutron stars and black hole - white dwarf binaries. We calculated merger properties and rates, and compared it with the current estimates from LIGO-Virgo-Kagra. In Trani et al. 2022b, we instead proposed a novel way to model the common envelope evolution in binary stars, which is a crucial phase in binary stellar evolution that is necessary to produce gravitational wave events. Further study accomplished in this fiscal year related to the stability of triple systems, which can affect the formation of merging compact binaries. Finally, we have implemented a novel way to model three-body interactions of compact objects in galactic nuclei. We are currently performing a study on: (1) the outcome properties of three-body encounters in galactic nuclei, to better understand how they differ with respect to isolated encounters. This enabled us to analyze the eccentricity of black hole mergers, which may enable us to distinguish from other mergers. (2) The interplay between Kozai-Lidov oscillations and encounters on compact binaries in galactic nuclei.
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