1. The Dark Age… before the stars, beyond the galaxies…

2. Overview of history of Universe …

3. The Dark Age … How do you study neutral hydrogen?

4. ??? How do you find H clouds ??? ??? How do you find HI clouds ???

7. Dutch Westerbork Telescope

8. Comparison: Hubble, Radio, very deep optical from ground

9. Energy Levels in Hydrogen E = 0 Ground State Energy Lyman Balmer Paschen

10. Emission Lines: from Photoionization Lyman alpha

11. Energy Levels in Hydrogen E = 0 Ground State Energy free electron Photo- ionization Recombination radiative decay

12. Energy Levels in Hydrogen E = 0 Ground State Energy To excite optical & UV lines …need at least 10.2 eV Hot Stars Quasars

13. Energy Levels in Hydrogen E = 0 Ground State Energy Hyperfine splitting of H ground state 21 cm line  E = 6 x 10 eV -6-6 thermally excited by collisions in cold gas

14. Comparison: Hubble, Radio, very deep optical from ground

25. Blue galaxies => young, massive stars

26. Red galaxies… What makes them RED ??? red stars redshift “reddening” (dust)

27. The `microwave sky’ (all sky picture from WMAP map.gfsc.nasa.gov)

28. WMAP:

29. The `microwave sky’ (all sky picture)

30. from Jordi Miralda-Escude 2003, Science, 300, 1904 1 10 100 1000 1 + Z Age of Universe [years] 10 10 10 9 10 8 10 7 10 6

31. The CMB

33. Gnedin’s simulation of Reionization: log(Neutral fraction) log(density) log T log(mean intensity of ionizing flux) http://casa.colorado.edu/~gnedin/GALLERY/

34. Energy Levels in Hydrogen E = 0 Ground State Energy free electron Photo- ionization Recombination radiative decay

35. High Z SDSS Quasar (Fan et al 2002) Gunn-Peterson Trough

36. Lyman Alpha Moderate Z Quasar Highest Z Quasar

37. Cut off from view of optical wavelengths !!! n HI n HI +n HII  10 -3 If neutral fraction >

38. Square Kilometre Array

39. ARRAY Simple antenna “elements” “Station” “Array”

40. D Sensivity depends on collecting area Angular resolution ~ /D

41. D Sensivity depends on collecting area Angular resolution ~ /D

42. VLA ALMA ESO VLTI

43. ARRAY Simple antenna “elements” “Station” “Array”

44. SKA Design “Magic Carpet”

45. Eggs on Legs

46. LOFAR = Low Frequency Array

47. on map of the Netherlands

48. 10 arcmin LOFAR and SKA … Quasar distributed star formation

49. LOFAR and SKA … Z = 13.5 12.8 12.0 11.3 10.6 9.9 9.3 8.7 8.1 log( neutral fraction ) Ciardi & Madau 2003