The Current State of Observational Cosmology

1. JPO: Cochin(05/01/04) The Current State of Observational Cosmology

2. 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”.

3. The Truth is More Complex… • We Know Some of the Components, But There Are Huge Gaps in Our Knowledge! • We Understand Some of the Phases, But Calculate Others Incorrectly, and for Others there Are Equally Valid, Non-Standard, Alternatives! • We Know Some Parameters to Percents, Others to Factors of Two and Others Are Uncertain to Order of Magnitude!

4. Foundation and Pillars.. • Homogeneous, Isotropic, Big Bang. • large scale uniformity (1930s -> present) • Hubble law (1930s -> present) • light element nucleosynthesis (1960s -> present) • temporal evolution observed directly (1960s -> present) • black body radiation field (1980s, 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 (Wtotal = 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. Foundation: General Relativity

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

12. Intellectual Paradigm: An Iterative Process • Pure Theory (or assumption). • Detailed and Massive Computation of Outcomes. • Global Astronomical Surveys to Check Predictions.

13. Primary Illustrative Examples • CBR Fluctuations (z ~1000, COBE & WMAP). • Lyman Alpha Clouds ( 6 > z > 3). • Galaxy Formation History ( 3 > z > 0). • Galaxy Surveys (z ~ 0).

14. Initial Conditions COBE:1991

15. Best Fit Concordance Model (Steinhardt, 2002)

16. WMAP (2002-2003)

17. WMAP CBR SKY

18. WMAP Spectrum

19. CBR:WMAP contributions • |n-1|/n << 1 = 0.01+-0.04. -> scale invariant spectrum • Wb / |Wm-Wb| << 1 = 17.1%+-0.25%. ->dark matter dominance • Wtot = 1.02 +- 0.04. ->flat universe 4) | hopt –hcbr | << 1 = 5%+-10%; confirmation 5) |s8cbr-s8clstr | / s8 << 1 = 0.29+-0.45; confirmation 6) tscat = 0.17+-0.04; a surprise Spergel et al: 2003

20. 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 yet available (needed to confirm re-ionization result).

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

22. Computing the Universe • Transformation to comoving coordinates x=r/a(t) • comoving cube, periodic boundary conditions • Lbox >>lnl Lbox

23. 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.

24. Multiscale Challenge dynamic range requirement: > 105 spatial > 1010 mass

25. 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 .

26. Testing Cosmological Models:Lyman Alpha Forest 5<z<2 Lbox~10 Mpc Intergalactic filaments at z=3 Zhang, Meiksin, Anninos & Norman (1998)

27. Simulated Spectrum

28. 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.

29. 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.

30. Direct Observations of Galaxy Formation History

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

32. Star Formation Cosmic History Springel and Hernquist (2002)

33. Large Scale Structure Surveys (1990s) • Gaussian random field dr(x) • Linear power spectrum P(k) COBE Las Campanas Redshift Survey

34. APO SDSS 2000s

35. Sloan Digital Sky Survey: 2003200,000 galaxies

36. Cmbgg OmOl CMB

37. Cmbgg OmOl CMB + LSS

38. Inflation

39. Testing inflation Cmbgg OmOl CMB

40. Testing inflation Cmbgg OmOl CMB + LSS

41. What’s the Matter?

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

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

44. How clumpy is the Universe? Cmbgg OmOl

45. How clumpy is the Universe? Cmbgg OmOl CMB

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

47. Neutrinos

48. Cmbgg OmOl CMB

49. Cmbgg OmOl CMB + LSS

50. Cmbgg OmOl CMB + LSS