Galaxies and Cosmology

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1 F. Combes P. Boisse A. Mazure A. Blanchard Galaxies and Cosmology Translated by M. Seymour With 192 Figures Springer

2 Contents General Introduction 1 1 The Classification and Morphology of Galaxies The Classification of Galaxies Hubble's Classification Scheme De Vaucouleurs's Revised Classification Scheme (1959) Other Elements of the Classification Luminosity Distributions The Luminosity Profile of Ellipticals The Luminosity Profile of Spirals 13 The Central Bulge 13 The Disc 14 The Vertical Structure Stellar Populations, the Distribution of Colour, and Evolutionary Models Stellar Populations The Distribution of Colour, Evolutionary Models The Statistical Properties of Galaxies The Luminosity Function Morphological Segregation 26 References 26 2 The Galactic Interstellar Medium Ionized Gas Ionized Regions of the Disc Emission Lines in the Nucleus Radio Emission 33 The Nature of the Emission 33 General Characteristics of the Emission Atomic HI Gas Excitation Global Properties. Correlations The Distribution of Atomic Hydrogen 41 The Radial Distribution 41

3 X Contents Interferometric Observations 44 The Spiral Structure HI Holes and the Connection with Star Formation Distortion, or Warp, of the Plane The Molecular Phase Excitation and the Conversion Ratio Global Properties. Correlations The Radial Distribution The Spiral Structure The Connection with Activity in the Nucleus Other Molecules. Abundances 61 References 62 3 The Kinematics and Masses of Galaxies Optical Determinations Methods The General Properties of Rotation Curves ,, Radio Determinations Spiral Arms Bars and Oval Distortions Distortion, or Warp, of the Plane Asymmetries Determination of the Mass Distribution Methods of Analysis 75 Disc Galaxies 75 Elliptical Galaxies The Mass-Luminosity Ratio The Tully-Fischer Law and Its Interpretations 80 Exercises 81 References 82 4 Elliptical Galaxies Spectroscopic Observations General Remarks Rotation Velocities The Three-Dimensional Shape Ellipticity Profiles Other Tests of the Three-Dimensional Shape Models of Elliptical Galaxies The Vlasov Equation and Jeans's Theorem Models of Spherical Galaxies 94 /( ) Systems 94 /(, J) Systems Models of Axisymmetric Galaxies 97

4 Contents XI Exercises 98 References The Spiral Structure of Galaxies Stellar Dynamics. Stability. Orbits Stability 102 Jeans Instabilities 102 Stability due to Rotation 103 The Stability Criterion Stellar Orbits 104 Epicycles 104 Lindblad Resonances 106 Surfaces of Section The Density-Wave Theory The Winding Problem 109 Stationary Density Waves or Stochastic Spirals? 110 Kinematic Waves The Wave Dispersion Relation 114 Obtaining the Dispersion Relation 115 Wave Propagation 120 Swing Amplification Shock Waves Induced in the Gas 123 The Continuous Interstellar Medium 124 Interstellar Clouds and the Warm Medium 127 Damping of the Waves Spiral-Wave Generation Mechanisms Angular-Momentum Transfer The Excitation of Spiral Waves by a Companion 131 Exercises 133 References Barred Galaxies Observations The Theory of Bar Formation Orbits in a Barred Galaxy The AT-Body Problem 146 Numerical Methods 146 Tests of Stability 147 The Ostriker-Peebles Criterion Equilibrium Perpendicular to the Plane The Response of the Gas to a Barred Stellar Potential Theory Gas-Cloud Simulations 157 Torques Exerted by the Bar on the Gas 158

5 XH Contents Comparison with Observations 161 Exercises 163 References Interactions between Galaxies Galactic Tides The Principles of Tidal Action Numerical Simulations 172 The Three-Body Problem 172 Taking Account of Dissipation The Formation of Filaments and Ring Galaxies 176 Filaments 176 'Coring' Galaxies Vertical Oscillations and Warps Differential Oscillations Vertical Waves and the Dispersion Relation Tidal Interaction and Warps Dynamical Friction Estimating the Frictional Force 189 Gravitational Deviation 189 Calculating the Braking Force 190 The Limitations of Chandrasekhar's Formula The Criteria for Merger 194 The Merger of Two Elliptical Galaxies 194 The Merger of Two Spiral Galaxies Shells around Elliptical Galaxies The Shell Formation Mechanism Sampling the Gravitational Potential of an Elliptical Galaxy The Three-Dimensional Shape of Elliptical Galaxies The Formation of Ellipticals. Conclusions 202 Exercises 204 References Extragalactic Radio Sources Physical Processes Radiation Emitted by an Ensemble of Relativistic Electrons The Internal Energy of agas Energy Losses Polarization of Radiation. Faraday Rotation The Various Types of Radio Source and Associated Optical Objects Compact Sources. Extended Sources The Optical Identification of Radio Sources 212

6 Contents 8.3 Extended Sources Observed Morphologies 213 Extended Edge-Brightened Double Sources 213 Extended Edge-Darkened Double Sources 214 Wide Double Sources 214 Sources with Two Tails 214 Sources with a Single Narrow Tail Morphological Classification The Intrinsic Size of Radio Sources The Spectrum and Polarization of Extended Lobes 216 Diffuse Emission 216 Hot Spots Radio Jets Symmetry, Shape, and Size The Spectrum and Polarization Lateral and Longitudinal Variation of the Radio Emission Optical and X-ray Emission Associated with Radio Jets Compact Sources The Radio Spectrum Variability Morphology, Changes of Structure, and Superluminal Velocities Radio-Source Modelling Radio-Source Counts. Evolution Expected Counts in the Absence of Evolution Observed Counts and Their Consequences The Size-Redshift Relation. Size Evolution 236 Exercises 237 References Quasars and Other Active Nuclei Emission from the Nucleus Continuous Emission 240 The Radio Domain 240 The Infrared Domain 241 The Optical and Ultraviolet Domains 242 The X-ray Domain Emission Lines 243 Permitted Lines 243 Forbidden Lines Variability and Polarization Systematic Quasar Searches The Radio Domain The Visible Domain 248

7 XIV Contents \ Selection Based on X-ray and Infrared Emission X The Spatial Distribution of Quasars The Distribution Projected on the Sky The Luminosity Function of Quasars Quasar Evolution Gravitational Lenses Characteristics of the Phenomenon An Example: The Gravitationally Lensed Quasar The Quasar Environment. The Nature of the Redshifts The Host Galaxies of Quasars The Nature of the Redshifts Other Classes of Active Nuclei Seyfert Galaxies BL Lac Objects Radio Galaxies Modelling Active Galactic Nuclei 263 Exercises 265 References The Absorption-Line Systems of Quasars General Remarks The Information Contained in Line Profiles The Identification of Absorption-Line Systems The Empirical Classification of Absorption-Line Systems Narrow-Metal-Line Systems._ The Redshift Distribution of the CIV and Mgll Systems and Its Implications The Physical Properties of the Absorbing Gas 276 The Velocity Dispersion 276 The Ionization State 277 The Size of the Haloes Damped Lymana Systems 279 Detection: Lymana and 21 cm Absorption 279 The Search for Associated Molecules: H 2 and CO 280 Dust The Direct Search for Absorbing Galaxies at Small z Narrow-Line Systems at z a fa z e Broad-Line Systems The Characteristics of QSOs with Broad Absorption Lines Modelling the Broad-Line Systems Lyman a Systems The Redshift Distribution Column Densities and the Velocity Dispersion 288

8 Contents XV The Heavy-Element Abundance Other Properties. Possible Models 289 Exercises 290 References The Universe on a Large Scale Structure and Homogeneity The Distance of the Galaxies: Probing the Universe The Third Dimension Statistical Methods: Correlation Functions and Percolation Correlation Functions Percolation Estimating the Mass of Groups and Clusters of Galaxies Large-Scale Motions. The Virgo Infall The Great Attractor Motion with Respect to the Cosmic Microwave Background Radiation 329 Exercises 331 References The Formation of Galaxies and Large Structures in the Universe The Jeans Mass and the Growth of Perturbations The One-Component Model The Two-Component Model Dark Matter The Origin, Spectrum, and Nature of the Fluctuations The Origin of the Fluctuations Isothermal and Adiabatic Fluctuations The Linear Evolution of Perturbations Nonlinear Evolution The Pancake Model The Hierarchical Scenario: The Spherical Model The Models in the Light of Observations Conclusions 353 Exercises 354 References Cosmology The Geometrical Description of the Universe The Redshift The Concept of Distance The Concept of Horizon The Evolution of the Cosmic Microwave Background Radiation 364

9 XVI Contents 13.2 Friedmann-Lemaitre Models The Matter-Dominated Universe Models with a Zero Cosmological Constant 368 Casel:J2 0 = l 368 Case 2: 2 0 < Case 3: 2 0 > Models with a Nonzero Cosmological Constant The Radiation-Dominated Universe The Hot Phase of the Universe The Thermal History of a Particle A Description of the Initial State of Equilibrium The Chemical Decoupling of a Particle Primordial Nucleosynthesis The Very Early Universe Problems of the Classical Big-Bang Theory and Grand Unified Theories The Theory of Inflation 387 The Horizon Problem 387 The Flatness Problem 388 Primordial Fluctuations 388 The Problem of Magnetic Monopoles 389 A Particular Phase Transition: Inflation Nonbaryonic Dark Matter 392 Exercises 394 References 394 List of Constants, Notation, and Units Used 397 Index 399

ACTIVE GALACTIC NUCLEI: FROM THE CENTRAL BLACK HOLE TO THE GALACTIC ENVIRONMENT

Julian H. Krolik ACTIVE GALACTIC NUCLEI: FROM THE CENTRAL BLACK HOLE TO THE GALACTIC ENVIRONMENT PRINCETON UNIVERSITY PRESS Princeton, New Jersey Preface Guide for Readers xv xix 1. What Are Active Galactic