1. NEUTRAL HYDROGEN Frank Briggs RSAA and ATNF z = 8 z = 0

2. damped Lyman-  abs-lines 21cm Line Studies (HIPASS)

3. Quasar Absorption lines Lyman  forest DLA Metal lines Wavelength (Angstroms) N >2x10 cm -2 20 HI

4. Quasar SiII CII SiII FeII AlII OI/SiII SiIV CIV HI D.L.A. (all DLAs have metal lines)

5. …bathe HI cloud in photoionizing radiation… Photons  E > 13.6 eV

6. …bathe HI cloud in photoionizing radiation… ?? minimum thickness of skin before becomes self-shielding ??

7. …bathe HI cloud in photoionizing radiation… optical depth  > 1 for  E ~ 13.6 eV photons N >3x10 cm -2 17 HI note:  < 1 … transparent… hard to heat!

8. Energy Levels in Hydrogen E = 0 Ground State Energy Optically thick at the Lyman limitOptically thick in the Lyman continuum Photons  E > 13.6 eV are absorbed transitions from ground state are absorbed

9. Energy Levels in Hydrogen E = 0 Ground State Energy Optically thick in the Lyman continuum BUT HI layer is transparent to all other wavelengths shorter than the Lyman limit

10. E = 0 Ground State Energy H He C N O Na Mg Al Si Ca Ti Cr Mn Fe Zn Ionization by ambient starlight with > 912 Angstrom

11. Quasar Absorption lines Lyman  forest DLA Metal lines Wavelength (Angstroms)

12. Quasar Absorption lines Lyman  forest DLA Metal lines LL

13. Quasar Absorption lines  thoroughly developed statistics !!! for Lyman  and metal lines… (whatever is common… is most likely to intervene by chance) (ordinary Galaxies

14. C IV M gII / Lyman limit (CII, FeII, SiII, …) Relative interception cross sections … Z=3 Ly break galaxyDLA

15. 12 14 18 20 22 HI Column density distribution function Petijean etal 1993 Log f (N HI ) -10 -15 -20 Log N HI Number of interceptions in range: N to N+dN f (N) dN per unit z N HI = N H (n HI / n H ) Ionization fraction ~10 -3 ? Ly  forest IGM DLA C IV  LL > 1

16. M ~ N f (N)dN HI f (N)dN ~ N dN /unit Z -3/2 12 14 18 20 22 HI Column density distribution function Petijean etal 1993 Log f (N HI ) -10 -15 -20 Log N HI DLA M / Log Interv ~ N f (N) HI 2 ~ N~ N +1/2

17. C IV M gII / Lyman limit (CII, FeII, SiII, …) Relative interception cross sections … What are these things??? Z=3 Ly break galaxyDLA (tough to image)pin

18. nearby Neutral gas disks analogs to high Z DLAs ??? Optical + Radio

19. Extended, low-column density gas = analog of LymanLimit/MgII CIV is the lower density material ??

20. Square Kilometre Array

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

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

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

24. VLA ALMA ESO VLTI

25. 6 th ATNF Synthesis Imaging Workshop “Synthesis Imaging from Centimetre to Millimetre Wavelengths” 12-16 May 2003 at Narrabri NSW www.atnf.csiro.au/synthesis

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

27. SKA Design “Magic Carpet”

28. Eggs on Legs

29. 3C196- G1 z = 0.437 HST image (Ridgway & Stockton) 3” Cohen et al

30. Double Lobed Radio Source Radio spectrum at 988 MHz Westerbork (Briggs, deBruyn, Vermeulen) 300 km/s

31. source centroid as fnct of Frequency map emission ? SKA map absorption ?

32. new GMRT Kanekar & Chengalur 988 MHz

33. high redshift radio galaxies TNR J2254+1857 TNR J1402-1510

34. Radio galaxy spectra No UV continuum No DLA absorption lines

35. Molonglo Telescope: SKAMP III frequency coverage sensitivity RFI rejection VLBI to resolve source

36. CosmicEvolutionIndicators Redshift 0 1 2 3 4 5 co-moving number density of bright Quasars Cosmic Star Formation Rate history: the Madau Plot 0 1 2 3 4 5 extent of metal-rich gaseous halos cosmic density  g of Neutral Gas 0 1 2 3 4 5

37. Violent accretion accretion Passive relaxation relaxation CosmicEvolutionIndicators Redshift 1420 500 250 MHz frequency

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

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

44. .…. ionized…… re-re-ionized re-ionized

45. MAP

46. Z = 17  ??? Rules out WDM MAP Result

47. 70 MHz ………………..180 MHz

49. Global Signal… 20 mK

50. “The Z=20 Expt” JR, FB, et al

51. Passband filters (from load scan) and RFI (from sky scan)

53. 10 arcmin LOFAR and SKA … Quasar distributed star formation

57. SUMMARY: still plenty to do !