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1、第25卷第5期 2008年9月中 国 科 学 院 研 究 生 院 学 报 Journal of the Graduate School of the Chinese Academy of SciencesVol.25 SeptemberNo.5 2008Article ID:100221175(2008)0520712209EXCERPT OF DISSERTATIONPopulating galaxies in dark matter halos3YANG Xiao2Hu1CHU Yao2Quan2(1Shanghai Astronomical Observatory,the Partner
2、 Group of MPA,Chinese Academy of Sciences,Shanghai200030 ,China;2Center for Astrophysics,University of Science and Technology of China,Hefei230026 ,China)(Received 24 March 2008)Yang XH, Chu YQ. Populating galaxies in dark matter halos.Journal of the Graduate School of the Chinese Academy ofSciences
3、, 2008 , 25(5) :712720Abstract In this paper we summarize part of our work presented in the thesis of Yang ,et al. entitled “The Statistical Research of Large Scale Structure in The Universe”. There are four chapters in thethesis: chapter 1 , the background of the large scale structure and galaxy fo
4、rmation; chapter 2 ,constructing a LAMOSTmock catalogue ; chapter 3 , the applicationsof the discrete wavelet transformationin the large scale structure studies; and chapter 4 , linking the galaxies with dark matter halos. Here wefocus on the work presented in chapter 4 , where we used the weak lens
5、ing measurements to constrain thegalaxy luminosity2dark matter halo relations and established a conditional luminosity function model (L|M) dL, which gives the number of galaxies with luminosities in the range (LdL)2 that residein a halo of massM. The conditional luminosityfunction derived from the
6、present data plays an importantrole in the establishing of the galaxy formation models and can help us to predict several statistics aboutthe distribution of galaxy light in the local Universe. We show that roughly 50 percent of all light isproduced in haloes less massive than 21012h- 1M .Key words
7、dark matter halos , large2scale structure of the universe , galaxies , theoryCLC P159153supported by the One Hundred Talents project , Shanghai Pujiang Program(07pj14102) ,973 Program(2007CB815402) ,the CAS Knowledge InnovationProgram(K JCX22YW2T05) and grants from NSFC (10533030 ,10673023)1 Introdu
8、ctionIt is well established that galaxies reside in extended dark matter haloes. Because of this , the standardassumptions in the current paradigmof structure formation are that a weakly interacting mass component (such as thecold dark matter , hereafter CDM) dominates the mass of the Universe and t
9、hat galaxies form by the cooling andcondensation of gas in dark matter haloes. Numerical simulations and analytical models can now give us a fairlydetailed picture of the abundance and clustering of CDM haloes1. However , in order to build a coherent picture ofgalaxy formation , we need to be able t
10、o link these propertiesof the halo population to those of the galaxy population.In other words , we need to know how dark matter haloes are populated by galaxies.Three different approaches have been used in the past to link galaxies to dark matter haloes. The first methodtries to infer the propertie
11、s of a halo from the properties of its galaxy population. The second method relies onabinitiomodels for the formation of galaxies , and the third method attempts to link the distributions of dark matterhaloes and galaxies using a more statistical approach.Mass estimates of individual dark matter hal
12、oes can be obtained from galaxy kinematics , from gravitationallensing , or from studying the X2ray haloes. However , each of these methods has its own shortcomings: kinematicsgenerally only probe the inner regions of dark matter haloes , results from gravitational lensing depend rathersensitively o
13、n the models adopted for the lensing systems , and X2ray measurements have to rely on the assumptionthat the gas is in hydrostatic equilibrium. In the first part of this paper , we will show how the observed weak lensingsignals can be used to constrain the mass2to2light relations2.An alternative app
14、roach is to buildab initiomodels for the formation of galaxies , using either large numericalsimulations3 ,4, (semi2)analytical models5 ,6, or a combination of both7 ,8. Although these methods have yieldedmany useful predictions about how dark matter haloes are populated by galaxies of different int
15、rinsic properties ,manyof the physical processes (such as star formation and feedback) involved are still poorly understood at thepresent and so some uncertain assumptions have to be made about a number of model ingredients such as theefficiency of star formation and feedback , the stellar initial m
16、ass function , and the amount of dust extinction.With the advent of large , homogeneous data sets such as the Two Micron All Sky Survey (2MASS) , the TwoDegree Field Galaxy Redshift Survey (2dFGRS) , and the Sloan Digital Sky Survey (SDSS) , it becomes possible toaddress the link between dark matter haloes and galaxies using a more statistical approach. The population ofgalaxies in individual haloes can formally be represented by a halooccupation function ,P(N|M) , which gives th
