2021 Fiscal Year Annual Research Report
| Project/Area Number |
21F51024
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| Allocation Type | Single-year Grants |
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| Research Institution | Chiba University |
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Principal Investigator |
石山 智明 千葉大学, 統合情報センター, 准教授 (90616426)
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| Co-Investigator(Kenkyū-buntansha) |
ELHASHASH MOHAMED 千葉大学, 統合情報センター, 外国人特別研究員
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| Project Period (FY) |
2021-11-18 – 2024-03-31
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| Keywords | 宇宙論 / 銀河団 / 銀河 / ダークマター |
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| Outline of Annual Research Achievements |
During my first six months of the JSPS fellowship, I have wrote a draft of "Constraining Cosmological Parameters using the Cluster Mass-Richness Relation", a manuscript that I will submit within a month to the Astrophysical journal. In this manuscript, I have studied the relationship between the richness (the number of galaxies within the cluster) and the cluster dynamical mass that includes baryonic and dark matter. Using this relationship, I have constrained the cosmological parameters of the matter density of the universe and the root mean square mass fluctuation. These two parameters are very important to measuring the amount of matter in the universe and understanding the formation of structures in the universe. I have used GalWCat19, a catalog of 1800 galaxy clusters. I identified in the Sloan Digital Sky Survey-DR13 spectroscopic data set using my GalWeight technique to determine cluster membership. I also have used the Uchuu N-body simulation, created by my host professor, and the illustris-TNG hydrodynamical simulation.
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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
I have started my next project of studying the correlations between properties of brightest cluster central galaxy and cluster masses to understand the environmental effect of the host clusters on the formation and evolution of central galaxies. Utilizing the GalWCat19 cluster catalog and Uchuu, nu2GC, and illustris-TNG simulations, we will study the relationships between the stellar mass of central galaxy and cluster dynamical mass. I have joint two research groups with my host professor. The first project is “Uchuu-SDSS light-cone”that aims at introducing some mock catalogs from the Uchuu N-body simulations. The catalogs will be publicly available to the astronomy community once it is ready. The second project is “Uchuu-UM” which aims at implementing the UniverseMachine method to generate mock data from the Uchuu N-body simulation. In this projects, we study the number density profiles of quiescent and star forming galaxies to understand the quenching process in clusters. Currently, I also study the environmental effects on galaxies in different overdense regions and dynamics of galaxy clusters as well. The projects aims at studying the galaxy size-mass relation and star formation rate of galaxies on the GalWCat19 cluster catalog as well as applying the GalWeight membership technique to the VIPERS galaxy surveys at high redshift (z~1) to construct a new galaxy cluster catalog.
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| Strategy for Future Research Activity |
I am planning to conduct a new project of studying the velocity dispersion proiles of galaxy clusters. An accurate measure of cluster mass is a critical task because all studies on large- and small-scales are strongly dependent on these measures. A large uncertainty in estimating dynamical cluster mass and extracting cosmological information is due to the bias between galaxies and dark matter subhalos. Comparing the velocity distribution of galaxies in clusters with those obtained from n-body and hydrodynamical simulations as well as semi-analytic model allows to understand the physical processes that govern this bias. Once we understand this bias, the cluster dynamical mass can be estimated with high accuracy. The idea is to generate templates of velocity dispersion proiles using simulations and then use these templates to estimate masses of observed clusters.
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