2021 Fiscal Year Final Research Report
A statistical test of the missing satellite problem in the CDM model
| Project/Area Number |
19H01942
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 16010:Astronomy-related
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 観測的宇宙論 / 近傍銀河 |
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| Outline of Final Research Achievements |
The missing satellite problem (inconsistency between the predicted number of satellite galaxies and that of observed ones) is one of the challenges to the standard cosmological model. We address this problem with a statistical sample of nearby galaxies observed with Hyper Suprime-Cam installed at the Subaru Telescope. We identify satellite galaxies around these nearby galaxies and compare their luminosity function with that of the Milky Way satellites. We find that the luminosity functions are consistent with each other. However, the Milky Way satellites tend to be located close to the Milky Way Galaxy, while external satellites are more uniformly distributed. This peculiar spatial distribution is one of the biggest results from our work. We do not know the origin of the peculiar distribution at this point and further work is needed here.
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| Free Research Field |
銀河天文学
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| Academic Significance and Societal Importance of the Research Achievements |
標準宇宙モデルのほつれの一つと指摘されるmissing satellite問題(モデルが予測する衛星銀河の数と、観測される数が合わない問題)をすばる望遠鏡を用いて統計的に検証したところ、天の川銀河の周囲を回る衛星銀河の数は、他の銀河の衛星銀河の数と整合的であることがわかった。しかしながら、その空間分布は大きく異なり、天の川銀河の衛星銀河が中心に偏った特異な分布をしていることがわかった。これは天の川銀河は宇宙の中で平均的な銀河ではないことを示唆していて、この特異分布の起源を理解するため、天の川銀河の形成史のさらなる研究が必要となる。
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