Concordance Cosmology: Is It Correct?

1. KITPC/ITP-CAS: Beijing (27/05/07) Concordance Cosmology: Is It Correct?

2. Question Answered: • Really Great Progress • Two Ways Physical Models are Tested/Falsified • A) Dramatic findings which overturn a paradigm; eg the late time acceleration of the galaxies. • B) Incremental Progress which exposes anomalies that will not go away; eg advance of the perihelion of Mercury. • ------------------------------------------------------------ The first, A, is not happening. Everything coheres. And experiments underway are reaching the precision to tell us if the second, B, will happen.

3. Now to the details. Presented historically.. Rumours of Great Progress… • We know the component pieces: Photons, Neutrinos, Baryons, Dark Matter & Dark Energy. • We know the history: Inflation, Baryogenesis, Dark Matter Domination, Growth of Structure, Dark Energy Domination. • We know the parameters: “Precision Cosmology”.

4. Foundation and Pillars.. • Homogeneous, Isotropic, Big Bang. • large scale uniformity (1930s -> present) • Hubble law (1930s -> present) • light element nucleo-synthesis (1960s -> present) • temporal evolution observed directly (1960s -> present) • black body radiation field (1960s, COBE -> present) • Baryons, Photons, Neutrinos, DM & DE. • Lyman alpha clouds, CBR spectrum (1960s -> present) • dark matter in clusters and halos (1930s, 1970s -> present) • supernovae show acceleration (2000s -> present)

5. Pillars contd… • Nearly Scale Invariant (n~1) Spectrum. • dimensional analysis (Harrison, Peebles & Zeldovich) (1960s) • inflationary (or ekpyorotic) theory(1980s -> present) • Fourier analysis of large scale structure(2000s) • Geometrical Flatness (total = 1). • Simplicity and dimensional analysis (1960s) • CBR spectrum, direct measurement of parts (2000s)

6. Each piece is supported by multiple arguments and measurements. Edifice is robust!

7. Foundations: General Relativity in an Homogeneous Isotropic Universe

8. The Universe is an Initial Value Problem….. • Globally, the universe evolves according to the Friedman equation: H2 H2 cosmological constant Hubble constant density parameter

9. In Dimensionless Form

11. Pillars: Observational Cosmology, 1920s -> 1970s

12. The Dawn of the Modern Era:1920-1950 • Harlow Shapley, Edwin Hubble, Walter Baade, Albert Einstein. • We live far off center in our galaxy. • The spiral nebulae are galaxies like our own Milky Way and are made of stars. • The galaxies are moving away from one another with a velocity proportional to the separation. • The laws of General Relativity rule in this domain.

13. The data would only have convinced a visionary!

14. The Heroic Era: 1950-1975 • Optical Observers use big telescopes to estimate the cosmological parameters. • Radio observers detect the cosmic background radiation field. • Theoreticians compute the cooking of the primal elements in the big bang. • Theoreticians speculate on the origins of structure.

15. Holmdel NJ: 1965 Penzias and Wilson discover a cosmic radio buzz in their antenna.

16. Calculations of the primal “cooking” of the chemical elements predict Hydrogen Helium Lithium etc, correctly! He D Li

17. A New Component - Dark Matter:1975-1995 • Clusters of Galaxies are Dark Matter Dominated (Zwicky: 1937). • Galaxy Halos are Dark Matter Dominated (Ostriker and Peebles: 1973). • Galaxy Rotation Curves require Dark Matter (Rubin:1978 ). • Perturbations Observed by COBE Satellite require Dark Matter (Mather: 1991).

18. Coma Cluster: 1000 galaxies (only center shown), 1000km/s held together by gravity from dark matter!

19. The Evidence from our Galaxy and other spirals shows that the total mass increases rapidly with increasing radius to far outside the visible galaxy. Visible galaxy

20. 1975-2002: Dark Energy, another New Component • The Universe must be older than the stars within it! • A “flat” universe, withtot = 1, is attractive and means m + e = 1. • Observations of distant supernovae indicate that the Universe is accelerating. • These arguments point to Dark Energy.

21. Supernova Observations show that the universe is accelerating!

22. The Inventory of the Universe Ordinary Chemical Elements Dark Energy Dark Matter 1 0 Omega

23. 1 1 1 0 0 0 1950 1975 2000

24. The COBE (1991) satellite confirmed the basic prediction of the big bang theory: the universe is filled with “black body radiation”.

25. With fluctuations – ripples – showing the seeds for all structure to be formed later. The height of the waves –1/100,000 – was more evidence for dark matter. COBE:1991

26. Best Fit Concordance Model (Steinhardt, 2002) NB: Rough fit to n=1 gaussian perturbation spectrum predicted by inlationary arguments or simple dimensional analysis.

27. 2002: The Model Has Passed Observational Tests at Various Epochs: eg • Z ~ 106 : Light Element Nucleosynthesis • Z ~ 103 : Cosmic Background Radiation • 6 > Z > 2 : Lyman alpha cloud absorptions • 4 > Z > 0 : Galaxy Formation Rate • Z ~ 0: Large Scale Structure of Galaxies

28. WMAP (2002-2007) Gives Initial Conditions

29. WMAP CBR SKY Page et al; 2003

30. WMAP Spectrum

31. CBR:WMAP initial contributions • |n-1|/n << 1 = 0.01+-0.04. -> scale invariant spectrum • b / |m-b| << 1 = 17.1%+-0.25%. ->dark matter dominance • tot = 1.02 +- 0.04. ->flat universe 4) | hopt –hcbr | << 1 = 5%+-10%; confirmation 5) |8cbr-8clstr | / 8 << 1 = 0.29+-0.45; confirmation 6) scat = 0.17+-0.04; a surprise Spergel et al: 2003

32. But… • Degeneracy in parameter estimation remains (so other measures are essential for accurate parameter estimation). • Low multi-poles are too low (a real issue or statistical fluctuations?). • E-E correlations not initially available (needed to confirm re-ionization result).

33. CBR Parameter Degeneracy Bridle, Lahav, Ostriker and Steinhardt: 2003

34. Computing the Universe: locally, growth of perturbations computed classically; numerical hydro required to reach the current epoch • Transformation to comoving coordinates x=r/a(t) • comoving cube, periodic boundary conditions • Lbox >>lnl Lbox Given initial conditions, compute forwards and test model at low red-shift. Remove/reduce degeneracy.

35. Physics Input • Newton’s law of gravitation. • Standard equations of hydrodynamics. • Atomic physics (for heating and cooling). • Radiative transfer. • [ Maxwell’s equations in MHD form ]. • ------------------------------------------------ • Heuristic treatment of star-formation.

36. Galaxy (L*,E0) Formation from High Resolution Hydrodynamic Simulation (Naab et al ‘07)

37. QSO Line Absorption from IGM • TVDPM on Large Eulerian grids. • Moderate over-density gas. • Metals, ionization state computed. • Line numbers and profiles computed. Hot gas filaments in the intergalactic medium Cen & Ostriker .

38. Simulated Spectrum

39. Lyman Alpha Clouds • Number of absorption lines vs redshift. • Number of absorption lines vs column density. • Velocity width distribution of lines. • Spatial correlation of line strengths. • -------------------------------------------- • All show good agreement:theory vs observation.

40. Evolution of Baryon Components Prediction confirmed: 30% -50% of baryons are in the WHIM: Confirmed.

41. Direct Observations of Galaxy Formation History

42. Star Formation Cosmic History Nagamine, Fukugita Cen and Ostriker (2001)

43. Large Scale Structure Surveys: Z~0 APO SDSS 2000s

44. Sloan Digital Sky Survey: 2003200,000 galaxies

45. Cmbgg OmOl CMB

46. Cmbgg OmOl CMB + LSS

47. How much dark matter is there? Cmbgg OmOl CMB

48. How much dark matter is there? Cmbgg OmOl CMB + LSS

49. How clumpy is the Universe? Cmbgg OmOl CMB

50. How clumpy is the Universe? Cmbgg OmOl CMB + LSS