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

The Dark Age… before the stars, beyond the galaxies…. Overview of history of Universe …. The Dark Age …. How do you study neutral hydrogen?. ??? How do you find H clouds ???. ??? How do you find HI clouds ???. Dutch Westerbork Telescope.

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

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  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 ???

  5. Dutch Westerbork Telescope

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

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

  8. Emission Lines: from Photoionization Lyman alpha

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

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

  11. -6 DE = 6 x 10 eV thermally excited by collisions in cold gas Energy Levels in Hydrogen E = 0 Hyperfine splitting of H ground state Energy 21 cm line Ground State

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

  13. Blue galaxies => young, massive stars

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

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

  16. WMAP:

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

  18. Age of Universe [years] 1010 109 108 107 106 1 10 100 1000 1 + Z 1 + Z from Jordi Miralda-Escude 2003, Science, 300, 1904

  19. The CMB

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

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

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

  23. Lyman Alpha Moderate Z Quasar Highest Z Quasar

  24. If neutral fraction nHI > ~10-3 nHI +nHII Cut off from view of optical wavelengths !!!

  25. Square Kilometre Array

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

  27. Sensivity depends on collecting area Angular resolution ~ l/D D

  28. Sensivity depends on collecting area Angular resolution ~ l/D D

  29. ESO VLTI ALMA VLA

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

  31. SKA Design “Magic Carpet”

  32. Eggs on Legs

  33. LOFAR = Low Frequency Array

  34. on map of the Netherlands

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

  36. 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

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