Interdisciplinary Advanced Research

Unified elucidation of the formation and evolution of the Universe by large innovative simulations
Associate Professor Tomoaki Ishiyama

The James Webb Space Telescope, launched by the National Aeronautics and Space Administration (NASA) at the end of 2021, and the Prime Focus Spectrograph (PFS), scheduled to be installed on the Subaru Telescope in 2023, are expected to dramatically advance observations of the first stars and galaxies and their relicsin the Milky Way. Although the formation and evolution of these objects have been theoretically studied in a cosmological context over the past 20 years, there is no direct observational evidence that these objects have ever existed, and a lot of their characteristics remain mysterious. For instance, where and how were the first stars and galaxies born? What role did they play in the evolution of the Universe?

We intend to conduct large-scale simulations using supercomputers, such as Fugaku, to elucidate the formation and evolution of these objects comprehensively. We intend to link large-scale simulations with different levels of hierarchy using advanced techniques, such as machine learning and high-performance big data processing. We also intend to follow the formation of galaxies in a spatial volume comparable to that of planning large-scale observations for the first time in the world, beginning with the formation of the first stars, which are the smallest components, and the black holes formed by the gravitational collapse of those stars. The project aims to construct mock catalogs that are qualitatively and quantitatively superior to currently popular ones. The catalogs will be made publicly available worldwide and developed into a standard theoretical template that is expected to be widely used over the long term. We will also make direct and precise comparisons between the mock catalogs and large-scale observations to clarify where and how the first stars and galaxies were born and what role they played in the evolution of the Universe.

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