2018 Fiscal Year Research-status Report
The identification and distribution of warm dark matter subhalos
| Project/Area Number |
17K14271
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Han Jiaxin 東京大学, カブリ数物連携宇宙研究機構, 客員准科学研究員 (50791456)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | dark matter / subhalo / clustering / matter distribution |
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| Outline of Annual Research Achievements |
After developing the HBT+ code for subhalo finding, in FY2018 we have applied the code to simulations to study the properties and distributions of halos and subhalos, as well as carrying out some observational studies of matter distribution around halos.On large scale, we carried out a multi-dimensional analysis of the clustering of central subhalos, to shed light on the origin of their assembly bias. For the first time, we are able to explicitly show that the dependences of bias on halo mass, concentration (or formation history), spin and shape are non-redundant with respect to each other, indicating their different physical origins. We also find that an environmental density is able to largely account for all the bias dependences. This reveals a new way to understand and model the large scale clustering of halos and subhalos. We have further used the subhalo catalog to develop a new algorithm for correcting for the fibre-collision effect in observational measurements of galaxy/halo clustering, and to study the lensing signal around low density regions in different cosmological models.On small scales, starting from simulated mergers of galaxies and subhalos, we developed a new code (StarGO) to identify substructures in the stellar halo around galaxies using a technique called self-organizing map. It can be applied to real observations such as the GAIA survey to study the small scale matter distribution and potentially constrain the property of dark matter. We have also used real observational data from HSC to study the stacked stellar halo around isolated galaxies.
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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 plan in FY2018 was to study the distribution and properties of dark matter halos and subhalos identified with our new code. We have studied the properties and clustering of halos and subhalos on both large and small scale, in both simulations and observations, covering both the dark matter and stellar components, and also extended to different cosmological models.
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| Strategy for Future Research Activity |
In FY2019 we plan to carry out more observational studies of the subhalo properties using weak gravitational lensing. We will produce and analyze more warm dark matter simulations to compare with the results in other cosmologies and to compare with observations.
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