F. Combes P. Boisse A. Mazure A. Blanchard Galaxies and Cosmology Translated by M. Seymour With 192 Figures Springer
Contents General Introduction 1 1 The Classification and Morphology of Galaxies 5 1.1 The Classification of Galaxies 5 1.1.1 Hubble's Classification Scheme 5 1.1.2 De Vaucouleurs's Revised Classification Scheme (1959)... 7 1.1.3 Other Elements of the Classification 9 1.2 Luminosity Distributions 11 1.2.1 The Luminosity Profile of Ellipticals 11 1.2.2 The Luminosity Profile of Spirals 13 The Central Bulge 13 The Disc 14 The Vertical Structure 14 1.3 Stellar Populations, the Distribution of Colour, and Evolutionary Models 16 1.3.1 Stellar Populations 16 1.3.2 The Distribution of Colour, 20 1.3.3 Evolutionary Models 22 1.4 The Statistical Properties of Galaxies 23 1.4.1 The Luminosity Function 23 1.4.2 Morphological Segregation 26 References 26 2 The Galactic Interstellar Medium 29 2.1 Ionized Gas 29 2.1.1 Ionized Regions of the Disc 29 2.1.2 Emission Lines in the Nucleus 32 2.1.3 Radio Emission 33 The Nature of the Emission 33 General Characteristics of the Emission 34 2.2 Atomic HI Gas 38 2.2.1 Excitation 38 2.2.2 Global Properties. Correlations 40 2.2.3 The Distribution of Atomic Hydrogen 41 The Radial Distribution 41
X Contents Interferometric Observations 44 The Spiral Structure 45 2.2.4 HI Holes and the Connection with Star Formation 46 2.2.5 Distortion, or Warp, of the Plane 49 2.3 The Molecular Phase 49 2.3.1 Excitation and the Conversion Ratio 49 2.3.2 Global Properties. Correlations 53 2.3.3 The Radial Distribution 53 2.3.4 The Spiral Structure 56 2.3.5 The Connection with Activity in the Nucleus 58 2.3.6 Other Molecules. Abundances 61 References 62 3 The Kinematics and Masses of Galaxies 63 3.1 Optical Determinations 63 3.1.1 Methods 63 3.1.2 The General Properties of Rotation Curves 64 3.2,, Radio Determinations 66 3.2.1 Spiral Arms 68 3.2.2 Bars and Oval Distortions 71 3.2.3 Distortion, or Warp, of the Plane 73 3.2.4 Asymmetries 74 3.3 Determination of the Mass Distribution 75 3.3.1 Methods of Analysis 75 Disc Galaxies 75 Elliptical Galaxies 77 3.3.2 The Mass-Luminosity Ratio 78 3.3.3 The Tully-Fischer Law and Its Interpretations 80 Exercises 81 References 82 4 Elliptical Galaxies 83 4.1 Spectroscopic Observations 83 4.1.1 General Remarks 83 4.1.2 Rotation Velocities 85 4.2 The Three-Dimensional Shape 87 4.2.1 Ellipticity Profiles 88 4.2.2 Other Tests of the Three-Dimensional Shape 88 4.3 Models of Elliptical Galaxies 93 4.3.1 The Vlasov Equation and Jeans's Theorem 93 4.3.2 Models of Spherical Galaxies 94 /( ) Systems 94 /(, J) Systems 96 4.3.3 Models of Axisymmetric Galaxies 97
Contents XI Exercises 98 References 100 5 The Spiral Structure of Galaxies 101 5.1 Stellar Dynamics. Stability. Orbits 101 5.1.1 Stability 102 Jeans Instabilities 102 Stability due to Rotation 103 The Stability Criterion 103 5.1.2 Stellar Orbits 104 Epicycles 104 Lindblad Resonances 106 Surfaces of Section 106 5.2 The Density-Wave Theory 107 5.2.1 The Winding Problem 109 Stationary Density Waves or Stochastic Spirals? 110 Kinematic Waves 112 5.2.2 The Wave Dispersion Relation 114 Obtaining the Dispersion Relation 115 Wave Propagation 120 Swing Amplification 121 5.2.3 Shock Waves Induced in the Gas 123 The Continuous Interstellar Medium 124 Interstellar Clouds and the Warm Medium 127 Damping of the Waves 128 5.3 Spiral-Wave Generation Mechanisms 129 5.3.1 Angular-Momentum Transfer 129 5.3.2 The Excitation of Spiral Waves by a Companion 131 Exercises 133 References 133 6 Barred Galaxies 137 6.1 Observations 137 6.2 The Theory of Bar Formation 139 6.2.1 Orbits in a Barred Galaxy 140 6.2.2 The AT-Body Problem 146 Numerical Methods 146 Tests of Stability 147 The Ostriker-Peebles Criterion 148 6.2.3 Equilibrium Perpendicular to the Plane 152 6.3 The Response of the Gas to a Barred Stellar Potential 153 6.3.1 Theory 154 6.3.2 Gas-Cloud Simulations 157 Torques Exerted by the Bar on the Gas 158
XH Contents Comparison with Observations 161 Exercises 163 References 165 7 Interactions between Galaxies 167 7.1 Galactic Tides 167 7.1.1 The Principles of Tidal Action 169 7.1.2 Numerical Simulations 172 The Three-Body Problem 172 Taking Account of Dissipation 173 7.1.3 The Formation of Filaments and Ring Galaxies 176 Filaments 176 'Coring' Galaxies 178 7.2 Vertical Oscillations and Warps 183 7.2.1 Differential Oscillations 183 7.2.2 Vertical Waves and the Dispersion Relation 185 7.2.3 Tidal Interaction and Warps 187 7.3 -Dynamical Friction 188 7.3.1 Estimating the Frictional Force 189 Gravitational Deviation 189 Calculating the Braking Force 190 The Limitations of Chandrasekhar's Formula 192 7.3.2 The Criteria for Merger 194 The Merger of Two Elliptical Galaxies 194 The Merger of Two Spiral Galaxies 194 7.4 Shells around Elliptical Galaxies 195 7.4.1 The Shell Formation Mechanism 195 7.4.2 Sampling the Gravitational Potential of an Elliptical Galaxy 200 7.4.3 The Three-Dimensional Shape of Elliptical Galaxies 200 7.5 The Formation of Ellipticals. Conclusions 202 Exercises 204 References 205 8 Extragalactic Radio Sources 207 8.1 Physical Processes 208 8.1.1 Radiation Emitted by an Ensemble of Relativistic Electrons 208 8.1.2 The Internal Energy of agas 209 8.1.3 Energy Losses 209 8.1.4 Polarization of Radiation. Faraday Rotation 210 8.2 The Various Types of Radio Source and Associated Optical Objects 210 8.2.1 Compact Sources. Extended Sources 210 8.2.2 The Optical Identification of Radio Sources 212
Contents 8.3 Extended Sources 213 8.3.1 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 215 8.3.2 Morphological Classification 215 8.3.3 The Intrinsic Size of Radio Sources 216 8.3.4 The Spectrum and Polarization of Extended Lobes 216 Diffuse Emission 216 Hot Spots 217 8.4 Radio Jets 217 8.4.1 Symmetry, Shape, and Size 218 8.4.2 The Spectrum and Polarization 220 8.4.3 Lateral and Longitudinal Variation of the Radio Emission.. 221 8.4.4 Optical and X-ray Emission Associated with Radio Jets... 222 8.5 Compact Sources 223 8.5.1 The Radio Spectrum 224 8.5.2 Variability 225 8.5.3 Morphology, Changes of Structure, and Superluminal Velocities 226 8.6 Radio-Source Modelling 230 8.7 Radio-Source Counts. Evolution 234 8.7.1 Expected Counts in the Absence of Evolution 234 8.7.2 Observed Counts and Their Consequences 235 8.7.3 The Size-Redshift Relation. Size Evolution 236 Exercises 237 References 238 9 Quasars and Other Active Nuclei 239 9.1 Emission from the Nucleus 240 9.1.1 Continuous Emission 240 The Radio Domain 240 The Infrared Domain 241 The Optical and Ultraviolet Domains 242 The X-ray Domain 243 9.1.2 Emission Lines 243 Permitted Lines 243 Forbidden Lines 245 9.1.3 Variability and Polarization 246 9.2 Systematic Quasar Searches 248 9.2.1 The Radio Domain 248 9.2.2 The Visible Domain 248
XIV Contents \ 9.2.3 Selection Based on X-ray and Infrared Emission 249 9.3 X The Spatial Distribution of Quasars 250 9.3.1 The Distribution Projected on the Sky 250 9.3.2 The Luminosity Function of Quasars 251 9.3.3 Quasar Evolution 252 9.4 Gravitational Lenses 253 9.4.1 Characteristics of the Phenomenon 254 9.4.2 An Example: The Gravitationally Lensed Quasar 0957+561 256 9.5 The Quasar Environment. The Nature of the Redshifts 258 9.5.1 The Host Galaxies of Quasars 258 9.5.2 The Nature of the Redshifts 260 9.6 Other Classes of Active Nuclei 261 9.6.1 Seyfert Galaxies 262 9.6.2 BL Lac Objects 262 9.6.3 Radio Galaxies 263 9.6.4 Modelling Active Galactic Nuclei 263 Exercises 265 References 266 10 The Absorption-Line Systems of Quasars 269 10.1 General Remarks 270 10.1.1 The Information Contained in Line Profiles 270 10.1.2 The Identification of Absorption-Line Systems 272 10.1.3 The Empirical Classification of Absorption-Line Systems.. 273 10.2 Narrow-Metal-Line Systems._ 273 10.2.1 The Redshift Distribution of the CIV and Mgll Systems and Its Implications 274 10.2.2 The Physical Properties of the Absorbing Gas 276 The Velocity Dispersion 276 The Ionization State 277 The Size of the Haloes 277 10.2.3 Damped Lymana Systems 279 Detection: Lymana and 21 cm Absorption 279 The Search for Associated Molecules: H 2 and CO 280 Dust 281 10.2.4 The Direct Search for Absorbing Galaxies at Small z 281 10.2.5 Narrow-Line Systems at z a fa z e 282 10.3 Broad-Line Systems 285 10.3.1 The Characteristics of QSOs with Broad Absorption Lines. 285 10.3.2 Modelling the Broad-Line Systems 286 10.4 Lyman a Systems 286 10.4.1 The Redshift Distribution 286 10.4.2 Column Densities and the Velocity Dispersion 288
Contents XV 10.4.3 The Heavy-Element Abundance 289 10.4.4 Other Properties. Possible Models 289 Exercises 290 References 291 11 The Universe on a Large Scale 293 11.1 Structure and Homogeneity 293 11.2 The Distance of the Galaxies: Probing the Universe 298 11.3 The Third Dimension 307 11.4 Statistical Methods: Correlation Functions and Percolation 312 11.4.1 Correlation Functions 312 11.4.2 Percolation 321 11.5 Estimating the Mass of Groups and Clusters of Galaxies 323 11.6 Large-Scale Motions. The Virgo Infall 327 11.6.1 The Great Attractor 327 11.6.2 Motion with Respect to the Cosmic Microwave Background Radiation 329 Exercises 331 References 331 12 The Formation of Galaxies and Large Structures in the Universe.. 333 12.1 The Jeans Mass and the Growth of Perturbations 334 12.1.1 The One-Component Model 334 12.1.2 The Two-Component Model 337 12.1.3 Dark Matter 338 12.2 The Origin, Spectrum, and Nature of the Fluctuations 339 12.2.1 The Origin of the Fluctuations 339 12.2.2 Isothermal and Adiabatic Fluctuations 339 12.3 The Linear Evolution of Perturbations 341 12.4 Nonlinear Evolution 346 12.4.1 The Pancake Model 346 12.4.2 The Hierarchical Scenario: The Spherical Model 347 12.5 The Models in the Light of Observations 349 12.6 Conclusions 353 Exercises 354 References 354 13 Cosmology 357 13.1 The Geometrical Description of the Universe 359 13.1.1 The Redshift 361 13.1.2 The Concept of Distance 362 13.1.3 The Concept of Horizon 364 13.1.4 The Evolution of the Cosmic Microwave Background Radiation 364
XVI Contents 13.2 Friedmann-Lemaitre Models 366 13.2.1 The Matter-Dominated Universe 367 13.2.2 Models with a Zero Cosmological Constant 368 Casel:J2 0 = l 368 Case 2: 2 0 < 1 368 Case 3: 2 0 > 1 369 13.2.3 Models with a Nonzero Cosmological Constant 370 13.2.4 The Radiation-Dominated Universe 373 13.3 The Hot Phase of the Universe 375 13.3.1 The Thermal History of a Particle 375 13.3.2 A Description of the Initial State of Equilibrium 376 13.3.3 The Chemical Decoupling of a Particle 377 13.3.4 Primordial Nucleosynthesis 379 13.4 The Very Early Universe 383 13.4.1 Problems of the Classical Big-Bang Theory and Grand Unified Theories 383 13.4.2 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 389 13.4.3 Nonbaryonic Dark Matter 392 Exercises 394 References 394 List of Constants, Notation, and Units Used 397 Index 399