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This thesis presents the measurement of the cosmic microwave background (CMB) power spectrum for the Atacama Cosmology Telescope (ACT) experiment and its polarized upgrade, ACTPol. I present the tools that I have developed for constructing unbiased and nearly optimal statistical estimators. I discuss how to separate the cosmological and the astrophysical signal and how to characterize instrumental systematics. The goal of this work is to obtain accurate power spectra measurement that can be used for cosmological parameter estimation. I first present the analysis of the complete ACT data set. The high resolution of the telescope allows us to recover power spectra to ℓ = 10000. I report the measurement of the power spectra at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. The power spectrum measurement is consistent with the ΛCDM model and a basic foreground model. I then present the cross correlation of maps from the Atacama Cosmology Telescope with maps from the Planck satellite in two overlapping regions covering 592 square degrees. I find excel- lent agreement between the two datasets at both frequencies, quantified using the variance of the residuals between the ACT power spectra and the ACT×Planck cross-spectra. The next generation of CMB experiments are focused on measuring its polarization. I present efficient algorithms for CMB lensing simulation and power spectrum estimation for flat-sky CMB polarization maps. Finally, I discuss the first temperature and polarization power spectra measurement from the ACTPol experiment. They are the first attempt to measure the polarization of the CMB at high resolution.

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Cheung Kai Chung Mars = 宇宙學中的題目 / 張啓聰. / Thesis submitted in: September 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 93-95). / Text in English; abstracts in English and Chinese. / Cheung Kai Chung Mars = Yu zhou xue zhong de ti mu / Zhang Qicong. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- "Hubble's Law, the cosmic scale factor and redshift" --- p.1 / Chapter 1.2 --- The Big Bang Model and Cosmic Microwave Background --- p.3 / Chapter 1.3 --- An overview of the universe --- p.4 / Chapter 1.4 --- Current Observation Results and Motivation --- p.6 / Chapter 1.5 --- Review of CMB calculation --- p.7 / Chapter 1.5.1 --- Friedmann Cosmologies --- p.8 / Chapter 1.5.2 --- The Perturbed Robertson-Walker Metric --- p.10 / Chapter 1.5.3 --- Boltzmann Equations --- p.13 / Chapter 1.5.4 --- Perturbative Einstein Equations --- p.16 / Chapter 2 --- Ionization History of The Universe --- p.18 / Chapter 2.1 --- Saha equation --- p.18 / Chapter 2.2 --- Peebles recombination --- p.19 / Chapter 2.3 --- RECFAST --- p.20 / Chapter 3 --- CMB Anisotropics --- p.22 / Chapter 3.1 --- The CMBA spectra --- p.23 / Chapter 3.1.1 --- Tight Coupling Limit --- p.23 / Chapter 3.1.2 --- Free Streaming --- p.25 / Chapter 3.1.3 --- The Anisotropy Spectrum --- p.27 / Chapter 3.1.4 --- CMBFAST --- p.28 / Chapter 4 --- Variation of Fundamental Constant and CMBA spectra --- p.30 / Chapter 4.1 --- The problem of units --- p.31 / Chapter 4.2 --- Modification of CMBFAST and conversion of units --- p.32 / Chapter 4.3 --- The constraints of varying constants using CMBA spectra --- p.35 / Chapter 4.4 --- Physics involved and variation of the spectra --- p.36 / Chapter 4.4.1 --- Effect of Recombination --- p.36 / Chapter 4.4.2 --- Variation of hP --- p.38 / Chapter 4.4.3 --- Variations of e and me --- p.41 / Chapter 4.4.4 --- Variations of g and c --- p.48 / Chapter 4.4.5 --- Constraints on the constants --- p.57 / Chapter 5 --- MCMC and CMBA Spectra --- p.59 / Chapter 5.1 --- Method --- p.60 / Chapter 5.1.1 --- Algorithm --- p.60 / Chapter 5.1.2 --- Check of Convergency --- p.61 / Chapter 5.2 --- Likelihood function --- p.62 / Chapter 5.3 --- Results --- p.66 / Chapter 5.3.1 --- MCMC investigation of varying α in the temperature spectrum --- p.67 / Chapter 5.3.2 --- MCMC investigation of varying α in the polarization spectrum --- p.69 / Chapter 5.3.3 --- MCMC investigation of varying α and cosmological parameters --- p.71 / Chapter 5.3.4 --- Summary --- p.73 / Chapter 6 --- Extra Dimensions and Cosmology --- p.74 / Chapter 6.1 --- A review of KK cosmology --- p.74 / Chapter 6.2 --- Non-flat extra dimension universe --- p.80 / Chapter 6.2.1 --- Close Extra Dimensions and Flat Usual Dimensions --- p.83 / Chapter 6.2.2 --- Open Extra Dimensions and Flat Usual Dimensions --- p.87 / Chapter 6.2.3 --- Summary: Possibility of Extra Dimension(s) --- p.91 / Bibliography --- p.93

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Chan Chi Wang = 宇宙微波背景輻射中之溫度與偏振各向不同性 / 陳志宏. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 94-98). / Text in English; abstracts in English and Chinese. / Chan Chi Wang = Yu zhou wei bo bei jing fu she zhong zhi wen du yu pian zhen ge xiang bu tong xing / Chen Zhihong. / Chapter 1 --- Overviewing modern cosmology --- p.1 / Chapter 1.1 --- Discoveries in Cosmology --- p.1 / Chapter 1.2 --- The Cosmological Model --- p.2 / Chapter 1.2.1 --- Cosmic Expansion --- p.3 / Chapter 1.2.2 --- The Metric and Friedmann Cosmology --- p.4 / Chapter 1.2.3 --- Thermodynamics of Matter and Radiation --- p.7 / Chapter 1.2.4 --- Timeline of the universe --- p.11 / Chapter 1.3 --- Formation of CMB and Its Anisotropics --- p.17 / Chapter 1.3.1 --- CMB --- p.17 / Chapter 1.3.2 --- CMB anisotropics --- p.18 / Chapter 1.4 --- Motivation and Thesis Outline --- p.21 / Chapter 2 --- The Recombination process --- p.23 / Chapter 2.1 --- The Saha approximation --- p.23 / Chapter 2.2 --- The Peebles recombination --- p.25 / Chapter 2.3 --- The RECFAST calculation --- p.28 / Chapter 3 --- The Boltzmann equations --- p.32 / Chapter 3.1 --- Boltzmann Equation for Photons --- p.33 / Chapter 3.1.1 --- Collision Term --- p.36 / Chapter 3.2 --- Boltzmann Equations for Matter --- p.37 / Chapter 3.2.1 --- Cold Dark Matter (CDM) --- p.37 / Chapter 3.2.2 --- Baryons --- p.38 / Chapter 3.3 --- Summary --- p.40 / Chapter 4 --- Formalism of CMB Anisotropies Calculation --- p.42 / Chapter 4.1 --- CMB Temperature Spectrum --- p.42 / Chapter 4.1.1 --- The Tight-coupling Solution --- p.43 / Chapter 4.1.2 --- Silk Damping --- p.45 / Chapter 4.1.3 --- The Free-Streaming Solution for fully decoupled cosmic fluid --- p.45 / Chapter 4.2 --- CMB Polarization Spectrum --- p.47 / Chapter 4.2.1 --- The E-mode and B-mode extractions --- p.48 / Chapter 4.3 --- The CMBFAST code --- p.50 / Chapter 4.4 --- Dependences on ionization history --- p.51 / Chapter 4.4.1 --- Recombination history --- p.53 / Chapter 4.4.2 --- Reionization history --- p.57 / Chapter 5 --- Softening of Equation of State during Recombination --- p.59 / Chapter 5.1 --- Recombination Revisited --- p.60 / Chapter 5.2 --- EOS softening by Recombination --- p.62 / Chapter 5.3 --- Numerical Results --- p.64 / Chapter 5.4 --- Summary and Discussions --- p.72 / Chapter 6 --- Time Varying Fundamental Constants --- p.74 / Chapter 6.1 --- Background --- p.74 / Chapter 6.1.1 --- Validity of time-varying fundamental constants --- p.76 / Chapter 6.1.2 --- The problem of units --- p.77 / Chapter 6.2 --- Theory --- p.78 / Chapter 6.3 --- Results --- p.79 / Chapter 6.3.1 --- Changing the electric charge --- p.80 / Chapter 6.3.2 --- Changing the electron mass --- p.82 / Chapter 6.3.3 --- Changing the cosmological constant --- p.85 / Chapter 6.3.4 --- Changing the speed of light --- p.87 / Chapter 6.4 --- Some concluding notes --- p.90 / Chapter 7 --- Conclusion --- p.92 / Bibliography --- p.94