El Universo en Expansion. Juan García-Bellido Inst. Física Teórica UAM Benasque, 12 Julio 2004

Transcription

1 El Universo en Expansion Juan García-Bellido Inst. Física Teórica UAM Benasque, 12 Julio 2004

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6 5 billion years (you are here)

7 Space is Homogeneous and Isotropic

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9 General Relativity An Expanding Universe

10 a 1 x 3 Euclidean space a 1 x 2 a 0 x 3 a 1 x 1 scale factor a ( t ) > a( t ) 0 1 a 0 x 2 a 0 x 1

11 λ λ obs em a = 0 = 1+ a 1 z

12 Mount Wilson Edwin P. Hubble

13 Mount Wilson Edwin P. Hubble Mount Palomar

14 Z=0.1 Z=0.6

15 Z=1.1 Z=1.6

16 Z=2.1 Z=2.6

17 Z=3.1 Z=3.6

18 Z=4.1 Z=4.6

19 Redshifts to galaxies Hubble law H 0 for d = z zc v < < 1

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21 HST Key Project

22 Hubble (1929) HST (1999) H 0 = 500km/s/Mpc H = 70 ± 7 km/s/mpc Dominated by 0 systematic errors! z 0. 1

23 The Accelerating Universe

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26 Supernovae la Lightcurves & Stretch-factor SNIa as Standard Candles

27 Riess et al. (2004)

28 Riess et al. (1998) Riess et al. (2004) SNIa Flat Universe Ω Ω M Λ = ± = 0. 71± 0. 05

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31 Normal Matter ρ < ρ 2 1 p > 0 d (ρv ) + pdv = TdS = 0 ρ = ρ 2 1 p < 0 Vacuum Energy

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34 The Aging Universe

35 If the universe is expanding, necessarily it must have been denser and hotter in the past Tracing the past history of the universe, we reach the realm of high energy physics and particle accelerators

36 T ( z) = T ( 1+ z) 0 a( z) a0 = ( 1 + z)

37 inflation now

38 inflation Large scale structure

39 inflation first galaxies

40 inflation microwave background

41 primordial nucleosynthesis

42 baryogenesis

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45 inflation

46 Quantum Fluctuations CMB Anisotropies Structure Formation

47 Inflationary Paradigm Why is the Universe spatially flat? Why is the Universe homogeneous on large scales? What is the origin of all matter and radiation? What is the origin of the fluctuations that gave rise to galaxies and other large structures?

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49 Constant Density GR Exponential growth Flatness

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51 Constant Density GR Exponential growth Flatness + Homogeneity + Reheating

52 Metric perturbations Quantum Fluctuations within the horizon

53 Scale Invariant Spectrum φ H 2π 2 e folds t H 1 1 e fold

54 Metric Perturbation λ a Enters horizon Horizon H d H 1 Exits horizon Inflation Radiation Matter z z end eq 0 z

55 After Inflation λ > d H λ d H λ < d H Outside Horizon Enters the Horizon Inside Horizon

56 Horizon Crossing λ a d H H 1 z dec Inflation Radiation Matter z z end eq z0

57 Φ(x) δ ρ (x) ρ Gaussian Random Field

58 Cosmic Microwave Background

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60 Discovery of CMB Arno Penzias Robert Wilson (1965) Blackbody Spectrum T=3K very isotropic

61 COBE ( )

62 T CMB = ± K

63 Temperature Anisotropies

64 COBE 4-year Measurements ( ) First Measurements Temperature Anisotropies (1992) T T

65 gravity Photon-Baryon Plasma in equilibrium: Thomson Scattering velocity density Metric Perturbation

66 Superhorizon Gravitational Potential Angular Power Spectrum Compression Rarefaction Subhorizon Acoustic Harmonic Oscillations Compression δt [ l( l + 1) Cl ] 1/ 2 Rarefaction Compression θ o = 180 θ o 0.8 l = 2 l 220 l θ 1

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68 All CMB Exp. (2002)

69 Best fit to all CMB data (2002)

70 Wilkinson Microwave Anisotropy Probe

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73 Wilkinson Microwave Anisotropy Probe (2003)

74 COBE (1992) 7 WMAP (2003) 10

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76 Cosmological Parameters: WMAP et al. Rate of expansion Age of the Universe Spatial Curvature Cosmological Constant Dark Matter Baryon Density Neutrino Density Spectral Amplitude Spectral tilt Tensor-scalar ratio H 0 = ± 71 3 km/s/mpc = ± 0 2 Gyr ΩK < ( 95% c. l.) Ω Λ = 0. 73± Ω M = 0. 23± Ω B = ± < ( 95% c. l.) A s = ± n s = 0. 93± r < ( 95% c. l.) Ω ν t 0.

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78 Structure Formation

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80 Φ(x) δ ρ (x) ρ Gaussian Random Field

81 Density Contrast Thresholds QSO First Stars Galaxies Clusters Superclusters Voids

82 z 1100 CMB Anisotropies z 100 Dark ages z 20 First stars z 10 Galaxies & Quasars z 1 Clusters & Superclusters

83 Large Scale Structure

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87 Numerical Simulations (beyond pert. Theory)

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90 Large Scale Structure Simulations (1996)

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93 Dark Matter

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103 Rotation curves of galaxies Ωdark 10 Ω stars

104 HST

105 t 0 H0 =. Ω M ± 0 05 = 0. 28± 0. 05

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107 log ρ Evolution Universe inflation radiation matter now? loga

108 Cosmic coincidence?

109 From Concordance to Standard Model

110 Cosmic Data (1999)

111 THE CONCORDANCE MODEL (2001)

112 EdS Age Universe STANDARD COSMOLOGICAL MODEL (2003) ΩM = ± ΩΛ = 0. 73± Ω0 = ± Ω = ± H B 0 = 71± 3km/s/Mpc t = ± 0. 2 Gyr 0 Precision Cosmology! Errors < few%

113 THE FUTURE MODEL (2010)

114 The Global structure of the universe

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118 Conclusions

119 Cosmology is becoming Cosmonomy, the science of measuring the Cosmos The stuff we are made of amounts to just a few percent of all the matter/energy Dark matter is here to stay. It could open the door to a new type of particle species (e.g. susy) Some kind of dark energy or smooth tension is responsible for the acceleration of the Universe. We have no idea of what it is We may measure our Local Universe but we ignore its Global Structure

120 The inflationary paradigm provides a general framework in which one can describe all cosmological observations The microwave background anisotropies contain a huge amount of information on the cosmological parameters, with very small systematic errors The Standard Cosmological Model, with errors of 1%, has two unsolved fundamental problems: the nature of dark matter and the dark energy

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123 Addendum

124 Friedmann equations a K G a a Λ + = ρ π + 00 ij Λ + + = ) ( p G a a ρ π 00 Equation of state of matter ) ( ) ( t w t p ρ =

125 Spatial curvature Closed K = +1 Flat K = 0 Open K = 1

126 Friedmann equation ( Λ = 0) 1 2 GM K a = 2 a 2 a K = 0 M K > 0 M E = T + = 4π 3 escape ρ V a recollapse 3 velocity K < 0 expand forever

127 Friedmann equation ( Λ 0) a GM Λ = + a F = m x a 2 3 Matter attraction Cosmic repulsion Who wins? and when?

128 Friedmann equation ( Λ 0) 1 2 GM 2 K a Λ a = E = T + V 2a62 V (a) a late times early times

129 Cosmological Parameters Rate of Expansion (Hubble) a H10 =)( t= hkm/s/mpc 0 a 0 1 = h 1 H Gyr time 1 = h ch Mpc distance 1 pc = ly = m

130 Critical density (K=0) ρ c ( t ) = 0 3H 2 0 8π G = h g/cm = h M /( h Mpc) Θ 3 2 = h protons/m 3

131 Density parameter Ω 0 = 8π G 3H 2 ρ ρ( t ) = ( t 0 0 ρ c ) Ω = Ω + Ω + Ω 0 R M Λ Friedmann Eq. Ω R = ρ ρ R c ( t ) 0 Ω M = ρ ρ M c ( t ) 0 Λ Ω K Ω = Λ 3H 2 K a 2 H =

132 H 0 t 0 = H 0 t 0 = 1. 0 H 0 t 0 = 0. 8 H 0 t 0 =. 0 7 H 0 t 0 =. 0 6 H 0 t 0 =. 0 5 Accelerating Decelerating Expansion Recollapse Closed Open Bounce

133 Cosmological Parameters H0 t0 q0 ΩK Rate of expansion Age of the Universe Acceleration Parameter Spatial Curvature ΩM ΩΛ ΩB Ων Dark Matter Cosmological Constant Baryon Density Neutrino Density