2010 Fiscal Year Final Research Report
The role of neutrinos in large scale structure of the universe and the determination of their masses
| Project/Area Number |
21740177
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Nagoya University |
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Principal Investigator |
ICHIKI Kiyotomo Nagoya University, 大学院・理学研究科, 助教 (10534480)
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| Project Period (FY) |
2009 – 2010
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| Keywords | 宇宙論 / 構造形成 / ニュートリノ |
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| Research Abstract |
We study the spherical, top-hat collapse model for a mixed dark matter model including cold dark matter (CDM) and massive neutrinos. By propely solving the Boltzmann equations for neutrino perturbations, we find that the neutrino cannot catch up with the nonlinaer evolution of CDM plus baryon perturbations due to its large free-streaming velocity, and consequently slow down the top-hat collapse up to most massive cluster scales. Our finding of the spherical collapse model suggests that, when the initial density fluctuations are normalized to the cosmic microwave background anisotropies, the presence of massive neutrinos decreases the expected present-day abudance of massive clusters with virial masses 10^15M〓 by more than about 20%.
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