Galactic and Extragalactic Radio Astronomy

ISBN-13: 9780387977355 / Angielski / Miękka / 1991 / 694 str.

Gerrit L. Verschuur; Kenneth I. Kellermann

Opis

Galactic and Extragalactic Radio Astronomy is a fundamental text for graduate students and professional astronomers and covers all aspects of radio astronomy beyond the solar system. Each chapter is written by a renowned expert in the field and contains a review of a particular area of radio astronomy and presents the latest observations and interpretations as well as an extensive view of the literature (as of 1988). Topics covered include: galactic continuum emission, HII regions, the diffuse interstellar medium, interstellar molecules, astronomical masers, neutral hydrogen, the galactic center, radio stars, supernova remnants, pulsars, extragalactic hydrogen, radio galaxies and quasars, the microwave background, and cosmological radio sources.

Spis treści

1. Galactic Nonthermal Continuum Emission.- 1.1 Introduction.- 1.1.1 Historical Preface.- 1.1.2 Early Surveys of Galactic Radio Emission.- a. Angular Distribution of the Cosmic Radio Waves.- b. Spectral Distribution of the Cosmic Radio Waves.- c. The Situation Circa-1956.- 1.2 Physical Processes.- 1.2.1 Synchrotron Radiation.- a. Single Particle Emission.- b. Radiation from an Ensemble of Particles.- c. Influence of the Medium.- 1.2.2 The Faraday Effect.- 1.3 Total Intensity Observations of the Galactic Radio Continuum.- 1.3.1 The Medium-Resolution Surveys.- 1.3.2 High-Resolution Surveys of the Galactic Plane.- 1.3.3 The Galactic Loops and Spurs.- 1.3.4 The Nonthermal Radiation and Galactic Structure.- 1.3.5 Galactic Radio Halo?.- 1.4 The Spectrum of the Nonthermal Emission.- 1.4.1 The Galactic Spectrum Above 10 MHz.- 1.4.2 The Very-Low-Frequency Spectrum.- 1.4.3 The Energy Spectrum of Cosmic-Ray Electrons.- 1.5 Linear Polarization of the Nonthermal Emission.- 1.5.1 Surveys of Linear Polarization of the Galactic Emission.- 1.5.2 Implications for the Local Magnetic Field.- 1.5.3 Magnetic Fields in the Galactic Loops.- 1.5.4 Rotation Measure Data and the Galactic Magnetic Field.- 1.6 The Galactic Nonthermal Radiation in Perspective.- Recommended Reading.- References.- 2. HII Regions and Radio Recombination Lines.- 2.1 Ionized Interstellar Hydrogen.- 2.1.1 Emission Nebulae.- 2.1.2 Diffuse Thermal Background.- 2.2 Radiation Transfer.- 2.3 Continuum Thermal Emission (Bremsstrahlung).- 2.3.1 Absorption and Emission Coefficients.- 2.3.2 Transfer Equation for Continuum Radiation.- 2.3.3 Low-Frequency Radiation from HII Regions.- 2.3.4 High-Frequency Radiation from HII Regions.- 2.3.5 Integrated Observations of HII Regions.- 2.3.6 Reality and the “Homogeneous Nebula” Approximation.- 2.3.7 Continuum Observations of HII Regions.- 2.3.8 Thermal Emission from Dust.- 2.4 Basic Theory of Radio Recombination Lines.- 2.4.1 Line Frequencies.- 2.4.2 Shape Function.- 2.4.3 Absorption and Emission Coefficients.- 2.4.4 Transfer Equation for Line Radiation.- 2.5 Refinements to the Transfer Equations.- 2.5.1 Local Thermodynamic Equilibrium.- 2.5.2 Departures from LTE.- 2.5.3 Turbulence Broadening.- 2.5.4 Pressure Broadening.- 2.6 Single-Dish Observations of Radio Recombination Lines from HII Regions.- 2.6.1 Early Observations of Integrated Line Intensities.- 2.6.2 Non-LTE Density-Gradient Models.- 2.6.3 Clumped Models.- 2.6.4 Comparison of the Density-Gradient and Clumped Models.- 2.6.5 Empirical Determinations of Electron Temperature.- 2.7 Exploration of the Milky Way by Radio Recombination Lines.- 2.7.1 Galactic Distribution of HII Regions.- 2.7.2 Galactocentric Variations of Electron Temperatures.- 2.7.3 Abundance Ratio of Helium to Hydrogen.- 2.7.4 The Diffuse Component.- 2.8 Radio Observations of HII Regions with High Angular Resolution.- 2.8.1 Continuum Observations.- 2.8.2 Recombination-Line Observations.- 2.9 Other Aspects of Radio Recombination Lines.- 2.9.1 Low Frequencies.- 2.9.2 Zeeman Effect.- 2.9.3 The Sun.- 2.9.4 Planetary Nebulae.- 2.9.5 Dark Clouds.- 2.9.6 Galaxies and Quasars.- Recommended Reading.- References.- 3. Neutral Hydrogen and the Diffuse Interstellar Medium.- 3.1 Introduction: Fundamentals.- 3.1.1 Radiative Transfer and Excitation of the HI Line.- 3.1.2 Observations of the Diffuse Medium.- a. Brief Review of the Four Phases: CNM, WNM, WIM, HIM.- b. Galactic Distribution of HI.- 3.1.3 Interstellar Pressure.- a.Excitation of CI Fine Structure.- b. Excitation of the CII Fine-Structure Lines.- c. Pressure of the WIM.- 3.1.4 Theory of the Kinetic Temperature of Diffuse Interstellar Gas.- a. Cooling Processes.- b. Heating Processes.- c. The Equilibrium Temperature.- d. Is Statistical Equilibrium Always Obtained?.- 3.1.5 Elements of Interstellar Gas Dynamics.- a. Static Equilibrium: The z-Structure in the Galaxy.- b. Static Equilibrium: A Uniform Spherical Magnetized Cloud.- c. Transient Features: Shocks.- 3.1.6 Two Famous Models of the Interstellar Medium.- 3.2 Structure of the Diffuse Interstellar Medium: HI Emission.- 3.2.1 Low-Velocity Gas.- a. Shells.- b. Filaments.- c. Major HI Concentrations Around Dark Clouds and Newly Formed Stars.- d. Shapes of HI Clouds.- e. Structure of HI Clouds.- 3.2.2 Intermediate-Velocity Gas.- 3.2.3 Supersheils and “Worms”.- 3.3 Temperature and Ionization of the Diffuse Interstellar Medium.- 3.3.1 HI Absorption: Techniques, Data, and Analysis.- a. Techniques and Data.- b. Derived Spin Temperature: Definition and Limitations.- 3.3 2 Temperature of Warm HI.- 3.3.3 Temperature of the Cold HI (CNM).- a. Classical Absorption Studies: The T-? Relation.- b. Statistics of Clouds.- 3.3.4 Temperature Structure of HI Clouds.- a. Temperature Structure and the T-? Relation.- b. Physical Implications.- 3.3.5 Ionization of the Diffuse Interstellar Medium.- a. Observations.- b. Ionization Within Diffuse Clouds.- c. Where Do the Electrons Reside?.- d. The Energy Source for the WIM.- 3.3.6 Filling Factors of the WIM, WNM, and CNM.- 3.4 Interstellar Magnetic Fields.- 3.4.1 Methods of Measurement.- a. B?: Linear Polarization of Starlight.- b. B?: Linear Polarization of Synchrotron Radiation.- c. B?: Linear Polarization of Radio-Wavelength Spectral Lines.- d. B?: Faraday Rotation.- e. B?: Zeeman Splitting.- f. Faraday Rotation Versus Zeeman Splitting.- 3.4.2 Fields in External Galaxies.- 3.4.3 The Galactic Field on Scales Above 100 pc.- a. The Field Strength.- b. The Field Direction.- 3.4.4 The Galactic Field on Scales of 100 pc and Below.- 3.5 Summary.- Recommended Reading.- References.- 4. Molecules as Probes of the Interstellar Medium MID of Star Formation.- 4.1 Introduction.- 4.1.1 Historical Perspective.- 4.1.2 The Central Role of Molecular Spectroscopy.- 4.2 The Large-Scale Morphology of the ISM.- 4.2.1 The Physical Regimes of the ISM.- a. “Coronal” Gas.- b. Intercloud Gas.- c. Diffuse Interstellar Clouds.- d. Cold Dark Clouds.- e. Globules.- f. Giant Molecular Clouds.- g. Hot Molecular Cores in GMCs.- 4.2.2 The Morphology of Dense Molecular Clouds.- 4.2.3 GMCs and Spiral Arms.- 4.3 The Nature of Star-Forming Regions.- 4.3.1 Small Star-Forming Cores in SMCs and GMCs.- 4.3.2 Massive Star-Forming Cores in GMCs.- 4.3.3 Large-Scale Relationships of Star-Forming Regions.- a. Low-Mass-Star-Forming Regions.- b. Massive-Star-Forming Regions.- 4.3.4 Intermediate-Scale Structure: Velocity Outflows and Disks.- 4.3.5 Magnetic Fields.- 4.3.6 Small-Scale Structure of Star-Forming Regions.- a. The Orion Molecular Core.- b. Other Star-Forming Cores.- 4.3.7 A Summary of Star Formation Morphology.- 4.4 The Stability of Molecular Clouds and Cores.- 4.4.1 Star Formation Rates and the Stability of Molecular Clouds.- 4.4.2 Global Relations Between (n, L, ?v) for Molecular Clouds.- 4.4.3 Rotation.- 4.4.4 Magnetic Fields.- 4.4.5 Stellar Winds.- 4.4.6 “Gravito-Turbulence” or “Star Cloud Turbulence”.- 4.5 The Formation of Stars.- 4.5.1 Low-Mass Stars from Low-Mass Cores.- 4.5.2 Formation of Massive Stars from Massive Cores.- a. A Summary of Observational Constraints.- b. Massive-Star Formation: Enhanced Accretion plus Shocks.- 4.5.3 A Stochastic Picture of Star Formation.- 4.6 Future Prospects.- 4.6.1 High-Resolution Studies of Star Formation.- a. Global Aspects As Seen in Other Galaxies.- b. Star-Forming Cores.- c. The Question of the Elusive “Protostar”.- d. Ori(KL) and Detailed Studies of Star-Forming Regions.- 4.6.2 Submillimeter and Far-IR Studies.- a. Far-IR Studies.- b. Submillimeter Studies.- Recommended Reading.- References.- 5. Interstellar Molecules and Astrochemistry.- 5.1 Molecules in Space: An Overview.- 5.1.1 A Brief History.- 5.1.2 The Presently Known Interstellar Molecules.- 5.1.3 Interstellar Chemistry: Some Generalities.- 5.2 Where Molecules Are Found: Basic Morphology of the Dense Interstellar Medium.- 5.2.1 Diffuse Clouds.- 5.2.2 Envelopes of GMCs and SMCs (“Dark Clouds”).- 5.2.3 Cold Cores and Low-Mass Star-Forming Cores in Molecular Clouds.- 5.2.4 Warm Massive Cores in GMCs.- 5.2.5 Shocked Regions.- 5.2.6 Circumstellar Envelopes.- 5.3 Molecular Abundances and Their Determination.- 5.3.1 Method of Analysis.- a. The Simplest Derivation of Column Densities.- b. Elementary Column Density Estimates When Many Transitions Are Observed.- c. Column Density Estimates from Radiative Transfer Techniques.- 5.3.2 Problems in Abundance Determinations.- a. Clumping.- b. Fractional Abundances.- c. Collisional Cross Sections.- d. Kinetic Temperature.- e. Radiation Fields.- 5.3.3 Representative Abundances.- 5.4 The Four Basic Schemes of Interstellar Chemistry.- 5.4.1 Ion-Molecule Chemistry.- 5.4.2 Surface Chemistry on Dust Grains.- a. Difficulties for Grain-Surface Chemistry: Diffuse and Cold Clouds.- b. Grain-Surface Chemistry in Warm Clouds.- c. Summary.- 5.4.3 Shock Chemistry.- 5.4.4 Circumstellar Chemistry.- a. Carbon-Rich Envelopes.- b. Oxygen-Rich Envelopes..- c. Summary.- 5.5 Current Dilemmas and Future Directions.- 5.5.1 The Composition of Interstellar Dust Grains.- 5.5.2 Diffuse Bands.- 5.5.3 Synthesis of Complex Molecules.- 5.5.4 Ring Molecules.- 5.5.5 NO Bonds.- 5.5.6 Chemistry Involving Second- and Third-Row Elements.- 5.5.7“Biological” Molecules.- 5.5.8 Unidentified Lines.- 5.5.9 A Final Perspective: What Has Astrochemistry Revealed?.- Recommended Reading.- References.- 6. Astronomical Masers.- 6.1 Introduction.- 6.2 Maser Theory.- 6.2.1 Radiative Transfer.- 6.2.2 Input Sources.- 6.2.3 Geometry and Apparent Sizes.- 6.2.4 Saturation.- 6.2.5 Line Widths.- 6.2.6 Polarization.- 6.2.7 Pump Models.- a. Interstellar Maser Pumps.- b. Stellar Maser Pumps.- 6.3 Interstellar Masers.- 6.3.1 H2O Masers.- 6.3.2 OH Masers.- 6.4 Stellar Masers.- 6.4.1 Supergiants.- 6.5 Extragalactic Masers.- 6.6 Interstellar Scattering.- 6.7 Distance Measurements.- Recommended Reading.- References.- 7. The Structure of Our Galaxy Derived from Observations of Neutral Hydrogen.- 7.1 Observations of Galactic Neutral Hydrogen.- 7.2 Kinematics of Galactic Neutral Hydrogen.- 7.2.1 Velocities Due to Differential Galactic Rotation.- 7.2.2 The Galactic Rotation Curve.- 7.2.3 Galactic Constants.- 7.2.4 Deviations from Circular Symmetry and Circular Motions.- 7.3 Mapping the Galaxy Using Neutral Hydrogen Observations.- 7.3.1 Line Profile Characteristics Caused by Geometrical Effects.- 7.3.2 Profile Characteristics Caused by Kinematic Irregularities.- 7.3.3 Some Remarks on the Spiral Structure of the Galaxy.- 7.4 The Inner-Galaxy Gas Layer.- 7.4.1 Radial Distribution of the Inner-Galaxy Gas and Dust Layer.- 7.4.2 Thickness and Flatness of the Inner-Galaxy Gas and Dust Layer.- 7.4.3 Other Parameters of the Inner-Galaxy Gas and Dust Layer.- 7.5 The Outer-Galaxy Gas Layer.- 7.5.1 The Shape of the Warped, Flaring, Outer-Galaxy Gas Layer.- 7.5.2 Some Characteristics of the Warped Gas Layer in Other Galaxies.- 7.5.3 Brief Remarks on the Phenomenon of High-Velocity Clouds.- Recommended Reading.- References.- 8. The Galactic Center.- 8.1 Introduction and Apologia.- 8.2 Radio Continuum Emission from the Provinces of Sagittarius.- 8.2.1 Sgr D.- 8.2.2 Sgr B.- 8.2.3 Sgr C.- 8.2.4 SgrE.- 8.2.5 Taking Stock of the Situation in the Provinces.- 8.3 Sgr A and Its Immediate Environment.- 8.3.1 The Compact Source Sgr A*.- 8.3.2 Sgr A East Is Both East and West.- 8.3.3 Sgr A West.- a. A Massive Rotating Ring.- b. A Small “Bar”.- 8.3.4 Sgr A* Redux.- 8.3.5 All the King’s Horses.- 8.4 Material in Sgr A Observed on 10- to 50-pc Scales.- 8.5 The Neutral Gas Reservoir in the Inner Galactic Regions.- 8.5.1 The “Expanding 3-kpc Arm”.- 8.5.2 A Tilted Disk—The Galaxy’s Bar?.- 8.5.3 More on the Central Gas Reservoir.- Recommended Reading.- References.- 9. Radio Stars.- 9.1 The Early Years.- 9.1.1 The Search for the Radio Sun.- 9.1.2 Early Flare Star Observations.- 9.1.3 When Is a Star a Radio Star?.- 9.1.4 The “Twilight” Years.- 9.1.5 The Dawn of Stellar Radio Astronomy.- 9.2 Fundamental Radio Emission Processes and Stellar Radiative Transfer.- 9.2.1 Radiative Transfer in Stellar Environments.- 9.2.2 Fundamental Radiation Processes.- a. Thermal Bremsstrahlung.- b. Magneto-Bremsstrahlung.- c. Thermal Versus Nonthermal and Incoherent Versus Coherent.- 9.3 Solar Radio Emission.- 9.3.1 Types of Solar Radio Emission.- 9.3.2 Quiet Sun Emission and the Slowly Varying Component.- 9.3.3 Enhanced Radio Emission Associated with Sunspots and Active Regions.- 9.3.4 Solar Noise Storms.- 9.3.5 Solar Radio Bursts.- a. Radio Emission Associated with First-Stage Flares.- b. Radio Emission Associated with Second-Stage Flares.- 9.3.6 The Solar Wind.- 9.4 Flare Stars and Active Binaries.- 9.4.1 Flare Star Radio Emission.- 9.4.2 “Radio-Active” Binaries—Particularly RS CVn’s.- 9.4.3 Pre-Main-Sequence Stars.- 9.5 Stellar Winds.- 9.5.1 Ionized Stellar Winds.- 9.5.2 Stellar Wind Observables.- 9.5.3 Cool, Weakly Ionized Winds.- 9.5.4 VV Cephei Binaries—Ionized Subregions of Cool Supergiant Winds.- 9.5.5 Symbiotic Stars—Interacting Winds and Ionized Subregions of Winds.- 9.6 Cataclysmic Variables.- 9.6.1 Classical Novae.- 9.6.2 Recurrent Novae.- 9.6.3 Dwarf Novae.- 9.6.4 Magnetic Cataclysmic Variables.- 9.7 Radio-Emitting X-Ray Binaries.- 9.7.1 Summary of Major Radio-Emitting X-Ray Binaries.- 9.7.2 Relativistic Jets and Synchrotron Flaring in Cyg X-3.- a. Cyg X-3 as a Sychrotron Flaring Source.- b. Cyg X-3 as a Relativistic Jet Source.- 9.7.3 Periodic Radio Variations in Cir X-l, LSI +61°303, and Cyg X-3.- 9.7.5 Relativistic Jets in SS433.- 9.7.5 Evolving Bubbles, Layers, and Cones of Relativistic Electrons.- a. Type of Geometry for Synchrotron-Radiating Regions.- b. Radio-Emitting Bubbles and Layers with Spherical Symmetry.- c. Evolution of Conical Radio Jets.- 9.7.6 Sco X-l—Radio Variable with Companion Double Radio Source.- 9.7.7 The Very Large Remnants Around SS433 and Cir X-l.- 9.7.8 Other X-Ray Binaries.- 9.7.9 Transient X-Ray/Radio Stars.- 9.7.10 A Unified View of Radio-Emitting X-Ray Binaries.- 9.8 Future Work on Radio Stars.- Recommended Reading.- References.- 10. Supernova Remnants.- 10.1 Introduction.- 10.1.1 History.- 10.2 Supernovae.- 10.2.1 Type I and Type II.- 10.2.2 Rates.- 10.3 Observed Properties of Supernova Remnants.- 10.3.1 Radio Characteristics.- 10.3.2 Optical Characteristics.- 10.3.3 X-Ray Characteristics.- 10.3.4 Variability.- 10.3.5 Statistics of Supernova Remnants.- 10.3.6 Radio Supernovae.- 10.4 Theory.- 10.4.1 Evolution.- 10.4.2 Relation of Evolutionary Theory to Observations.- 10.4.3 Crablike Supernova Remnants.- 10.4.5 Nonthermal Emission from Supernova Remnants.- 10.4.6 Radio Supernovae.- 10.5 Collective Interactions of Supernova Remnants with the Galaxy.- 10.5.1 Structure of the Interstellar Medium.- 10.5.2 Energy and Mass Input into the Interstellar Medium.- 10.5.3 Cosmic Rays.- 10.6 Future Prospects.- Recommended Reading.- Catalogues of Galactic Supernova Remnants.- References.- 11. Pulsars.- 11.1 Introduction.- 11.1.1 Brief History of Neutron Stars.- 11.1.2 New Types of Pulsars.- 11.2 Basic Properties.- 11.2.1 Intensity Spectra.- 11.2.2 Dispersion and Distance Scale.- 11.2.3 Pulse Timing.- 11.2.4 Standard Model of Emission Mechanism.- 11.3 Pulse Morphology and Polarization.- 11.3.1 Pulse Components.- 11.3.2 Polarization.- 11.3.3 Hollow-Cone Beam Model.- 11.3.4 More Polarization Effects.- 11.3.5 A Beam Model.- 11.3.6 Interpulses and Steady Emission.- 11.4 Intensity Fluctuations.- 11.4.1 Micropulses.- 11.4.2 Subpulses.- 11.4.3 Periodic Subpulse Phenomena.- 11.4.4 Pulse Nulling.- 11.4.5 Other Modulations.- 11.5 Interstellar Propagation.- 11.5.1 Neutral Hydrogen Absorption.- 11.5.2 Thermal Plasma Dispersion.- 11.5.3 Birefringence.- 11.5.4 Secular Variations of Path Integrals.- 11.5.5 Diffraction Caused by Interstellar Turbulence.- a. Thin-Screen Model.- b. Pulse Broadening.- c. Scintillation.- d. Scattering Measure.- 11.5.6 Refraction by Interstellar Turbulence.- 11.6 Timing and Astrometry.- 11.6.1 Time of Arrival Measurements.- 11.6.2 Time of Arrival Analysis.- 11.6.3 Interpretation of Pulsar Spin Properties.- 11.6.4 Astrometry.- 11.7 Binary and Millisecond Pulsars.- 11.7.1 The New Pulsars.- 11.7.2 Timing a Binary Pulsar.- 11.7.3 Timing a Millisecond Pulsar.- 11.8 Radio Emission Mechanism.- 11.8.1 Basic Requirements.- 11.8.2 Emission Site.- 11.8.3 Polar-Cap Models.- 11.9 Origin and Evolution.- 11.9.1 Introduction.- 11.9.2 Galactic Distribution.- 11.9.3 Period Evolution.- 11.9.4 Binary Pulsar Evolution.- Recommended Reading.- References.- 12. Extragalactic Neutral Hydrogen.- 12.1 Introduction.- 12.1 1 The Role of Neutral Hydrogen in Galaxies.- 12.1.2 The Information in the 21-cm Line.- 12.1.3 Pictorial Presentation of HI Data.- 12.2 The Distribution of HI in Galaxies.- 12.2.1 Morphology.- 12.2.2 Sizes.- 12.2.3 Warps.- 12.2.4 Appendages.- 12.3 Velocity Fields.- 12.3.1 Rotation Curves.- 12.3.2 Distortions in the Velocity Field.- 12.3.3 The Mass Distribution in Spiral Galaxies.- 12.3.4 Dark Matter in Dwarf Galaxies.- 12.4 The Velocity Width as a Distance Indicator.- 12.4.1 The Velocity Width-Magnitude Relation.- 12.4.2 Deviations from Hubble Flow.- 12.5 HI Content and Other Global Properties.- 12.5.1 Relations Between Global Properties for Spirals (Sa and Later).- 12.5.2 HI Content of Early-Type Galaxies.- 12.6 Environmental Effects.- 12.6.1 Tidal Interactions.- 12.6.2 Gas Deficiency in Cluster Spirals.- 12.7 Cosmological Studies.- 12.7.1 21-cm Redshift Surveys.- 12.7.2 Voids and the Segregation of Galaxian Properties.- 12.7.3 HI in Active Galaxies.- 12.7.4 HI in Quasars and in Their Spectra.- Recommended Reading.- References.- 13. Radio Galaxies and Quasars.- 13.1 Introduction.- 13.1.1 Optical Counterparts.- a. Historical Background.- b. Radio Galaxies.- c. Quasars.- 13.1.2 Radio Source Properties.- 13.1.3 Radio Spectra.- 13.1.4 Energy Considerations.- 13.2 Low-Luminosity Sources.- 13.2.1 Spiral, Seyfert, and Irregular Galaxies.- 13.2.2 Elliptical Galaxies.- 13.3 Compact Sources.- 13.3.1 Self-Absorption.- 13.3.2 Inverse Compton Radiation.- 13.3.3 Polarization.- 13.3.4 Structure.- 13.3.5 Variability.- 13.3.6 Source Dynamics and Superluminal Motion.- 13.3.7 Relativistic Beaming.- 13.4 Extended Sources.- 13.4.1 Jets, Lobes, and Hot Spots.- 13.4.2 Jet Physics.- a. Straight Jets.- b. Bent Jets.- 13.5 Summary.- Recommended Reading.- References.- 14. The Microwave Background Radiation.- 14.1 Introduction.- 14.1.1 The Discovery.- 14.1.2 Cosmological Setting.- 14.2 The Spectrum of the Microwave Background.- 14.2.1 Summary.- 14.2.2 Heterodyne Radiometer Methods (? ? 3 mm).- 14.2.3 Bolometric Measurements (? ? 3 mm).- 14.2.4 Measurements Using Interstellar Molecules.- 14.2.5 Summary and Future Prospects.- 14.3 Polarization of the Microwave Background.- 14.4 Anisotropy Searches.- 14.4.1 Small-Scale Measurements.- a. A Scenario.- b. Measurements.- c. Constraints on Cosmological Models.- d. Near-Future Improvements.- 14.4.2 Measurements of Large-Scale Structure.- a. A Scenario.- b. Measurements.- c. Likely Near-Future Improvements.- 14.5 The Sunyaev-Zel’dovich Effect.- 14.5.1 Concept and Cosmological Consequences.- 14.5.2 Measurements.- 14.5.3 Cosmological Applications.- Recommended Reading.- References.- 15. Radio Sources and Cosmology.- 15.1 Introduction.- 15.2 Basic Relations.- 15.3 The “World Picture” and Source Evolution.- 15.4 Source Population Data.- 15.4.1 The Local Luminosity Function.- 15.4.2 Source Counts.- 15.4.3 Spectral-Index Distributions.- 15.4.4 Redshift/Spectral-Index Diagrams.- 15.4.5 Redshift and Luminosity Distributions of Strong Sources.- 15.4.6 Optical Constraints.- 15.5 Evolutionary Models.- 15.5.1 Source Distribution Equations.- 15.5.2 Evolutionary Models of Radio Luminosity Functions.- 15.6 Source Size Evolution.- 15.6.1 The Angular Size-Redshift Relation.- 15.6.2 The Angular Size-Flux Density Data.- 15.6.3 Models of the Angular Size-Flux Density Relation.- 15.7 The Faint-Source Population.- 15.8 Isotropy and Homogeneity.- 15.9 Cosmology Made Simple: The Shell Model.- 15.10 What Next?.- Recommended Reading.- References.