Contents

OBSERVATIONALCOSMOLOGY

Introduction9 Chapter 1Space and time11 Introduction11 1.1 Olbers’paradox 11 1.2 Olbers’paradox in adifferent way12 1.3 Metrics: theUniverseinanutshell 13 1.4 Redshift andtimedilation19 1.5 Cosmological parameters21 1.6 Theage of theUniverse25 1.7 Theflatnessproblem 27 1.8 Distance in awarpedspacetime28 1.9 Theedge of theobservableUniverse31 1.10 Measuring distances andvolumes 32 1.11 Thefate of theUniverse35 Chapter 2The cosmic microwave background 40 Introduction40 2.1 Thediscovery of thecosmicmicrowavebackground 40 2.2 TheCMB temperature as afunctionofredshift42 2.3 Whyisthe CMB ablack body? 45 2.4 Baryogenesis46 2.5 Theentropyper baryon 47 2.6 Primordial nucleosynthesis: athousandseconds that shaped the Universe 47 2.6.1The primordialfireball 47 2.6.2The primordialelementabundances 50 2.7 Theneed for newphysics 52 2.8 Theinflaton field 57 2.9 Theprimordial density powerspectrum 60 2.10 Thereal musicofthe spheres 67 2.11 TheCMB dipole 70 2.12 Theacoustic peaksinthe CMB 72 2.13 TheSachs–Wolfeeffect 74 2.14 Reionization 76 2.15 Cosmological parameter constraints 76 2.16 Thepolarization of theCMB 79 2.17 Dark energy andthe fate of theUniverse83

5 Contents

Chapter 3The local Universe 92 Introduction92 3.1 Evidence for dark matter 92 3.2 TheHubbletuning fork94 3.3 Spiral galaxies andthe Tully–Fisherrelation 96 3.4 Thefundamental planeofelliptical galaxies 98 3.5 Clustersofgalaxies 99 3.6 TheSunyaev–Zel’dovich effect 100 3.7 Themorphology–density relation102 3.8 TheButcher–Oemler effect 104 3.9 Thecoolingflow problem105 3.10 Thecosmological distance ladder 105 3.11 Thelarge-scale structure of theUniverse108 3.12 Baryon wiggles 116 Chapter 4The distant optical Universe 120 Introduction120 4.1 Source counts120 4.2 Colddarkmatter andstructure formation 121 4.3 Population synthesis129 4.4 Photometric andspectroscopicredshifts 132 4.5 Luminosity functions135 4.6 Active galaxies 139 4.7 Deep-field surveysand wide-field surveys144 4.8 Morphological K-corrections154 4.9 Thebluecloud andred sequence154 Chapter 5The distant multi-wavelength Universe 159 Introduction159 5.1 Theextragalactic optical andinfrared background light 159 5.2 Submmgalaxies andK-corrections162 5.3 Ultraluminous andhyperluminous infraredgalaxies 166 5.4 Measuring star formation rates 169 5.5 Multi-wavelengthsurveys173 5.6 Cosmicstar formation history andstellar mass assembly 174 5.7 Downsizing 177 5.8 Feedback in galaxyformation 178 Chapter 6Black holes183 Introduction183 6.1 What areblack holes?183 6 Contents

6.2 TheEddington limit 185 6.3 Accretion efficiency 188

6.4 Cosmicmassdensity of black holes, ΩBH 193 6.5 Finding supermassive black holes 195 6.5.1Context195 6.5.2Stellar andgas kinematics 196 6.5.3Megamasers197 6.5.4Stellar proper motion198 6.5.5Broadiron X-rayemissionline198 6.5.6Reverberationmapping 199 6.6 TheMagorrian relation201 6.7 ThehardX-raybackground 203 6.8 Black holedemographics 207 6.9 Observationsofblack holegrowthand theeffects of feedback 207 6.10 Merging black holes andgravitationalwaves 210 Chapter 7Gravitational lensing216 Introduction216 7.1 Gravitationallensdeflection 216 7.2 Thelensequation220 7.3 Magnification 222 7.4 Thesingular isothermal sphere model227 7.5 Time delaysand theHubbleparameter 229 7.6 Caustics andmultiple images 231 7.7 Otherlensmodels 236 7.8 Microlensing237 7.9 Cosmicshear 240 7.10 Galaxycluster lenses 246 7.11 Finding gravitationallenses249 Chapter 8The intervening Universe253 Introduction253 8.1 TheLyman α forest 253 8.2 Comparison with cosmological simulations 257

8.3 Ωb andthe cosmicdeuterium abundance257 8.4 Thecolumndensity distribution258 8.5 Damped Lyman α systems261 8.6 Theproximity effect 266 Ω 8.7 H I,the neutral hydrogen density parameter 267 8.8 Howbig areLyman α clouds?269 7 Contents

8.9 Reionization and the Gunn–Petersontest270 8.10 TheLyman α forest of He II 273 8.11 Thefirstlight in theUniverseand gamma-rayblazars275 8.12 TheSquare KilometreArray277 8.13 TheCODEXexperiment278 Epilogue282 AppendixA 283 AppendixB 285 Solutions291 Acknowledgements312 Index318

8