INTRODUCTIONThe Standard ParadigmFundamental Physics in the CMBHistoryIntroduction to the Angular Power SpectrumCurrent Understanding of the Temperature FieldAcoustic OscillationsHow Spatial Modes Look Like Angular AnisotropiesCMB PolarizationProcesses after Decoupling: Secondary AnisotropiesWhat We Learn from the CMB Power SpectrumDiscussion of Cosmological ParametersFOREGROUNDSOverviewForeground RemovalMETHODS OF DETECTIONThe CMB Experiment BasicsThe Detection TechniquesObserving StrategiesTechniques of Data AnalysisFUTURE PROSPECTSThe Next Satellite ExperimentCONCLUDING REMARKSACKNOWLEDGMENTSThe Cosmic Microwave Background for Pedestrians:A Review for Particle and Nuclear PhysicistsDorothea Samtleben1)Suzanne Staggs2)Bruce Winstein3)1) Max-Planck-Institut f¨ur Radioastronomie, Bonn 2) Princeton University3) The University of ChicagoContents1 INTRODUCTION 21.1 The Standard Paradigm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Fundamental Physics in the CMB . . . . . . . . . . . . . . . . . . . . . . . . 31.3 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.4 Introduction to the Angular Power Spectrum . . . . . . . . . . . . . . . . . 61.5 Current Understanding of the Temperature Field . . . . . . . . . . . . . . . 71.6 Acoustic Oscillations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.7 How Spatial Modes Look Like Angular Anisotropies . . . . . . . . . . . . . 81.8 CMB Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.9 Processes after Decoupling: Secondary Anisotropies . . . . . . . . . . . . . 111.10 What We Learn from the CMB Power Spectrum . . . . . . . . . . . . . . . 131.11 Discussion of Cosmological Parameters . . . . . . . . . . . . . . . . . . . . . 152 FOREGROUNDS 172.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.2 Foreground Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 METHODS OF DETECTION 203.1 The CMB Experiment Basics . . . . . . . . . . . . . . . . . . . . . . . . . . 213.2 The Detection Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.3 Observing Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.4 Techniques of Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 FUTURE PROSPECTS 304.1 The Next Satellite Experiment . . . . . . . . . . . . . . . . . . . . . . . . . 315 CONCLUDING REMARKS 326 ACKNOWLEDGMENTS 33AbstractWe intend to show how fundamental science is drawn from the patterns in thetemperature and polarization fields of the cosmic microwave background (CMB) radi-ation, and thus to motivate the field of CMB research. We discuss the field’s history,potential science and current status, contaminating foregrounds, detection and analy-sis techniques and future prospects. Throughout the review we draw comparisons toparticle physics, a field that has many of the same goals and that has gone throughmany of the same stages.1arXiv:0803.0834v1 [astro-ph] 6 Mar 20081 INTRODUCTIONWhat is all the fuss about noise? In this review we endeavor to convey the excitementand promise of studies of the cosmic microwave background (CMB) radiation to scientistsnot engaged in these studies, particularly to particle and nuclear physicists. Although thetechniques for both detection and data processing are quite far apart from those familiar toour intended audience, the science goals are aligned. We do not emphasize mathematicalrigor1, but rather attempt to provide insight into (a) the processes that allow extractionof fundamental physics from the observed radiation patterns and (b) some of the mostfruitful methods of detection.In Section 1, we begin with a broad outline of the most relevant physics that can beaddressed with the CMB and its polarization. We then treat the early history of thefield, how the CMB and its polarization are described, the physics behind the acousticpeaks, and the cosmological physics that comes from CMB studies. Section 2 presents theimportant foreground problem: primarily galactic sources of microwave radiation. Thethird section treats detection techniques used to study these extremely faint signals. Thepromise (and challenges) of future studies is presented in the last two sections. In keepingwith our purposes, we do not cite an exhaustive list of the ever expanding literature onthe subject, but rather indicate several particularly pedagogical works.1.1 The Standard ParadigmHere we briely review the now standard framework in which cosmologists work and forwhich there is abundant evidence. We recommend readers to the excellent book ModernCosmology by Dodelson (2). Early in its history (picoseconds after the Big Bang), theenergy density of the Universe was divided among matter, radiation, and dark energy.The matter sector consisted of all known elementary particles and included a dominantcomponent of dark matter, stable particles with negligible electromagnetic interactions.Photons and neutrinos (together with the kinetic energies of particles) comprised theradiation energy density, and the dark energy component some sort of fluid with a negativepressure appears to have had no importance in the early Universe, although it is responsiblefor its acceleration today.Matter and radiation were in thermal equilibrium, and their combined energy densitydrove the expansion of space, as described by general relativity. As the Universe expanded,wavelengths were stretched so that particle energies (and hence the temperature of theUniverse) decreased: T(z) = T(0)(1 + z), where z is the redshift and T(0) is the tem-perature at z = 0, or today. There were slight overdensities in the initial conditions that,throughout the expansion, grew through gravitational instability, eventually forming thestructure we observe in todays Universe: myriad stars, galaxies, and clusters of galaxies.The Universe was initially radiation dominated. Most of its energy density was inphotons, neutrinos, and kinetic motion. After the Universe cooled to the point at whichthe energy in rest mass equaled that in kinetic motion (matter-radiation equality), theexpansion rate slowed and the Universe became matter dominated, with most of its en-ergy tied up in the masses of slowly moving, relatively heavy stable particles: the protonand deuteron from the baryon sector and …