| 研究実績の概要 |
The purpose of the research project was to develop a new method to find subhaloes in warm dark matter simulations and to model their distributions, based on modifications and extensions to the HBT algorithm. As a first step, in FY2017 we have developed a much improved version of the original HBT code, HBT+, which is much faster, more user friendly, and more complete in physics. We have also built a FoF halo finder into HBT+, in order to explore halo finding in warm dark matter simulations with varying linking length. We have applied HBT+ to the Millennium-II simulation and the Aquarius simulation, and have obtained much improved results in the halo merger-tree as well as the subhalo mass function. In particular, we have shown that HBT+ finds a more abundant population of massive subhaloes in the center of host haloes, and the spatial and mass distribution of these subhaloes deviate from the universal distribution for low mass ones, reflecting that the massive subhaloes are more resilient to tidal stripping. These results are in contrast to the subhalo distribution found by conventional subhalo finders that work in configuration space, and are in better agreement with recent gravitational lensing observations of the subhalo population in galaxy clusters. We have also used our results to investigate the distribution of haloes in different epoches and over different scales, to improve our understanding about the progenitor population of subhaloes. The merger tree built from HBT+ has also been used to study the dynamical status of Milky-Way size haloes.
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