十月天文论坛
Xiaohu Yang
Shanghai Astronomical Observatory
Beijing, 16/10/2012
Constrain cosmological parameters using observations
调和宇宙学
4% Atoms, 23% Cold Dark Matter, 73% Dark energy.
Concordance LCDM model
从调和宇宙学到精确宇宙学
Dark matter
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Galaxy
Two types of investigations to make the link
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From (theoretical) halos: model the galaxy formation/distribution
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The hydrodynamical simulations
The semi-analytical galaxy formation models
Statistical modelling: the HOD/CLF models
From (observational) galaxies: model the halo (mass) distribution
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Clusterings
Clusters
Galaxy-galaxy lensing
Satellite kinamatics
X-ray clusters
S-Z effect
(I) 大尺度结构和宇宙学
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Large redshift surveys:
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The correlation functions and power spectra of galaxies
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To constrain cosmology and galaxy formation
N-body and hydro simulations:
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LAMOST
Using public data releases
国际合作：AS3，BigBOSS，LSST
To understanding the structure formation and galaxy formation
Other related work
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21cm, etc
伍向平等（第一缕曙光）；李菂等（FAST）；陈学雷等（天籁）；SKA
等
Lensing
毛淑德等
LAMOST team:
(1)建设团队
(2)运行团队
(3)科学团队
(1)河外
(2)河内
几乎所有的国内天文单位都有某种程度的参与。
HOD: understanding the clustering of galaxies
(1)景益鹏等（HOD）；
(2)褚耀泉等（成团测
量）；
(3)冯珑珑等（小波）
(4)詹虎等（LSST）；
(5)杨小虎等（CLF)
(6)盘军（3PCF）
(7)李成（SDSS）
(8)张骏（lensing）
(9)范祖辉（lensing）
(10)陈学雷（再电离）
(11)张鹏杰
(12)王慧元、王宇
Jing et al. 1998
Hierarchical structure formation: from C4
We have a C4 ( Chinese Computational
Cosmology Consortium) collaboration
in China.
Including members from: SHAO,
PMO, NAOC, SCCAS
景益鹏、冯珑珑、高亮、林伟鹏、
盘军、康熙、赵东海、杨小虎、张
鹏杰等
(II) 星系团
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Clusters are the rarest objects in the Universe.
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They were extensively used to probe the cosmological parameters.
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To obtain the reliable measure of the halo masses, detailed studies of cluster properties are
necessory.
Extreme environment to probe the galaxy formation.
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They locate at the exponential decay region of the halo mass function.
Their clusterings show the largest bias.
Because of the hierarchical strucutre formation, their member galaxies are accreted at
different redshift.
Serve as the strong lens to find the highest redshift galaxies.
The halo mass function and bias
Galaxy clusters
Sheth et al. (2001)
Clusters for cosmology -- 过去
精确宇宙学
• 寻求和暗晕质量精确挂钩
• 提高观测的完备度。
• 整合多种观测结果，减小系
统误差。
Eke et al. (1996)
现状： more than cosmology
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Optical clusters.
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From spectroscopic surveys: cosmology, galaxy formation
From photometric surveys: strong lensing candidates, cosmological probes
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X-ray clusters
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Observations: completeness? Cool core clusters?
Hydrodynamical simulations to understand the gas properties
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徐海光等；伍向平等；朱宗宏等；方涛涛等
Strong and weak lensing signals
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Observations, model the mass distributions
Giant arcs, constrain the cosmology
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杨小虎等；文中略等
毛淑德等；付丽萍等；李国亮等；景益鹏等；张骏等
S-Z effect
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Theoretical modellings, detectablity
Stacking to get a few sigma detection
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张鹏杰等；李然等；盘军等
每个方向都有若干课题组在从事相关研究工作；上述列表很不完全。
New App (1): Probe the galaxy formation
Giocoli et al. 2010
Question: the faint end slope of the LFs in clusters?
Rines & Geller 2008
New App (2): improve the completeness
(1) We extracted 1138 (RASS) X-ray
clusters from liturature.
(2) About 200 are cross-matched with
SDSS DR7 optical groups.
(3) The vast majority of the optical
groups are not linked with any
known entries.
(4) We run our own (Growth Curve
Analysis) GCA code to obtain the
X-ray signals from the RASS map.
Optical - X-ray clusters cross-identification
Wang et al. 2011
(5) An additional ~10000 X-ray
signals are obtained for groups
with mass > 10^{13}Msun.
New App (3): using clusters as lens to find the first galaxies
A few slides from Zheng Wei’s talk in Hefei, May 8, 2012.
Candidate Galaxy at z=9.6
May 8, 2012
USTC
Summary
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Clusters are the rarest objects in the Universe.



They were extensively used to probe the cosmological parameters.






To obtain the reliable measure of the halo masses, detailed studies of cluster properties are
necessory.
Optical clusters
X-ray clusters, gas properties
Strong lensing signals
SZ effect
Extreme environment to probe the galaxy formation.


They locate at the exponential decay region of the halo mass function.
Their clusterings show the largest bias.
Because of the hierarchical strucutre formation, their member galaxies are accreted at
different redshift.
Serve as the strong lens to find the first galaxies.