Wandering in the Background:
A Cosmic Microwave Background Explorer
W.Hu
Abstract
We develop and examine the principles governing the formation of distortions in the cosmic microwave background. Perturbations in the frequency or spectral distribution of the background probe the thermal history of the universe, whereas those in the angular temperature distribution probe its dynamics and geometry. Stressing model independent results, we show how the microwave background can be used to extract information on the mass density, vacuum density, baryon content, radiation content, expansion rate and some aspects of structure formation in the universe. To address these issues, we develop elements of relativistic kinetic and perturbation theory as they become necessary for the description of the particle and gravitational interactions of the photons. Subtle issues such as fluctuation representation, or gauge, normal mode analysis in an open geometry, and second order effects are considered in detail. Employing analytic and numerical results, we construct anisotropies in a critical, open, and cosmological constant universe with adiabatic and/or isocurvature initial conditions allowing for possible early reionization. We find that anisotropy formation is a simple process governed by the Compton scattering of photons off electrons and their gravitational coupling to the other particle species in the universe.
Front Material (158K PDF) | i |
--List of Figures | viii |
--List of Tables | x |
--Preface | xi |
--Acknowledgements | xiii |
1. Overview (417K PDF) | 1 |
--1.1 Cosmological Background | 1 |
--1.2 Anisotropy Formation | 6 |
--1.3 Anisotropy Spectrum | 18 |
--1.4 Robustness to Initial Conditions | 20 |
--1.5 Reionization | 22 |
2. Boltzmann Equation (265K PDF) | 25 |
--2.1 Gravitational Interactions | 26 |
--2.2 Compton Scattering | 31 |
3. Thermalization and Spectral Distortions (638K PDF) | 43 |
--3.1 Collision Equations | 44 |
--3.2 Thermalization Optical Depths and Rates | 47 |
--3.3 Low Frequency Evolution | 57 |
--3.4 High Frequency Evolution | 66 |
--3.5 Comparisons and Constraints | 73 |
4. Multifluid Perturbation Theory (346K PDF) | 81 |
--4.1 Normal Mode Decomposition Theory | 82 |
--4.2 Newtonian Gauge Evolution | 88 |
--4.3 Gauge | 97 |
5. Perturbation Evolution (467K PDF) | 107 |
--5.1 Superhorizon Evolution | 108 |
--5.2 Subhorizon Evolution before Recombination | 117 |
--5.3 Matter Evolution after Recombination | 127 |
6. Primary Anisotropies (1.4MB PDF) | 131 |
--6.1 Overview | 131 |
--6.2 Sachs-Wolfe Effect | 135 |
--6.3 Acoustic Peaks | 152 |
7. Secondary Anisotropies (636K PDF) | 161 |
--7.1 Linear Contributions | 162 |
--7.2 Second Order Contributions | 176 |
--7.3 Beyond Perturbation Theory: A Survey | 184 |
--7.4 Final Thoughts | 186 |
Bibliography (80K PDF) | 188 |
A. Toward Higher Accuracy: A CDM Example | 197 |
--A.1 Refining the Gravitational Potentials | 198 |
--A.2 Analytic Construction to 5% Accuracy | 203 |
--A.3 Toward 1% Accuracy | 210 |
B. Useful Quantities and Relations (232K PDF) | 219 |
--B.1 FRW Parameters | 219 |
--B.2 Time Variables | 221 |
--B.3 Critical Scales | 226 |
--B.4 Normalization Conventions | 229 |
--B.5 Symbol Index | 233 |
SLAC citations