Dark and luminous matter in galaxies and large scale structure

In this dissertation, I investigate the transverse proximity effect in Lyalpha transmitted flux, the baryon fraction and stellar mass-to-light ratio in early-type galaxies, and the relation between dark matter halos and optical observables of galaxy clusters.;The proximity effect is the observed reduction in absorption by HI in the Lyalpha forest in the proximity of QSOs. This effect was explained as the excess ionization from QSO and used to investigate the background QSO emission intensity. However, in some of the observations, there is only very weak or no proximity effect observed at all. This might arise from the QSOs residing in higher density regions. In this chapter, I investigate the effect of enhanced density close to QSOs with synthetic spectra from smoothed particle hydrodynamics (SPH) simulations at redshifts z = 2, z = 3, and z = 4. By modeling the halo mass-QSO luminosity relationship, we compare the expected effect from the enhanced density and that from excess QSO photoionization. The influence of the QSO flux increases with redshifts, with more absorptions around low mass halos and much higher transmitted flux close to high mass halos.;To investigate the baryon fraction and the evolution of the stellar mass-to-light ratio in early-type galaxies, the joint gravitational lensing and stellar dynamical analysis of fifteen massive field early-type galaxies are used. The following numerical results are found: (i) A joint-likelihood gives an average logarithmic density slope for the total mass density of ⟨gamma'⟩ = 2.01+0.02-0.03 (68% C.L.; rhotot ∝ r-gamma' ) inside ⟨REinst⟩ = 4.2 +/- 0.4 kpc (rms of 1.6 kpc). The inferred intrinsic rms spread in logarithmic density slopes is sigmagamma' = 0.12, which might still include some minor systematic uncertainties. (ii) The average position-angle difference between the light distribution and the total mass distribution is found to be ⟨Deltatheta⟩ = 0 +/- 3 degrees (rms of 10 degrees), setting an upper limit of ⟨gammaext⟩ ≲ 0.035 on the average external shear. The total mass has an average ellipticity ⟨qSIE⟩ = 0.78 +/- 0.03 (rms of 0.12), which correlates extremely well with the stellar ellipticity, q*, resulting in ⟨q SIE/q*⟩ = 0.99 +/- 0.03 (rms of 0.11) for sigma ≳ 225 kms-1. (iii) The average projected dark-matter mass fraction is inferred to be ⟨fDM⟩ = 0.25 +/- 0.06 (rms of 0.22) inside ⟨RE⟩, using the stellar mass-to-light ratios derived from the Fundamental Plane as priors. (iv) Combined with results from the Lenses Structure & Dynamics (LSD) Survey at z ≳ 0.3, we find no significant evolution of the total density slope inside one effective radius for galaxies with sigmaap ≥ 200 kms -1: a linear fit gives alphagamma' ≡ d⟨gamma'⟩/dz = 0.23 +/- 0.16 (1sigma) for the range z=0.08--1.01. We conclude that massive early-type galaxies at z=0.06--0.33 on average have an isothermal logarithmic density slope inside half an effective radius, with an intrinsic spread of at most 6% (1 sigma).;Based on the galaxies hosted by halos more massive than 1013.5 M⊙ from the Millennium Run Simulation (MRS), the relations between the halo mass and cluster optical observables are investigated, at redshifts z = 0, z = 0.3, and z = 0.5 are investigated. Two simulated galaxy catalogs are used, with one from the Durham university group, and the other from Max Planck Institution for Astrophysics (MPA) group. The relations between halo mass and cluster luminosity, or halo mass and galaxy richness (galaxy number) can be well fit by power-law mean relations with lognormal scatter. The scatter is around 0.12 dex (Durham) and 0.15 dex (MPA) at cluster luminosity Ltot 101.4L*. The scatter in the Durham simulation decreases with increasing cluster luminosity, while no obvious trend appears in the MPA simulation. The central galaxy luminosity is also correlated with halo mass, but with larger scatter. At fixed halo mass, there is little or no correlation of average galaxy luminosity or central galaxy luminosity with richness. The mean relations and scatter show little evolution between z = 0.5 and z = 0. (Abstract shortened by UMI.)...