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
Comparison: Hubble, Radio, very deep optical from ground
Energy Levels in Hydrogen E = 0 Ground State Energy Lyman Balmer Paschen
Emission Lines: from Photoionization Lyman alpha
Energy Levels in Hydrogen E = 0 Ground State Energy free electron Photo- ionization Recombination radiative decay
Energy Levels in Hydrogen E = 0 Ground State Energy To excite optical & UV lines …need at least 10.2 eV Hot Stars Quasars
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
Comparison: Hubble, Radio, very deep optical from ground
Blue galaxies => young, massive stars
Red galaxies… What makes them RED ??? red stars redshift “reddening” (dust)
The `microwave sky’ (all sky picture from WMAP map.gfsc.nasa.gov)
WMAP:
The `microwave sky’ (all sky picture)
from Jordi Miralda-Escude 2003, Science, 300, Z Age of Universe [years]
The CMB
Gnedin’s simulation of Reionization: log(Neutral fraction) log(density) log T log(mean intensity of ionizing flux)
Energy Levels in Hydrogen E = 0 Ground State Energy free electron Photo- ionization Recombination radiative decay
High Z SDSS Quasar (Fan et al 2002) Gunn-Peterson Trough
Lyman Alpha Moderate Z Quasar Highest Z Quasar
Cut off from view of optical wavelengths !!! n HI n HI +n HII If neutral fraction >
Square Kilometre Array
ARRAY Simple antenna “elements” “Station” “Array”
D Sensivity depends on collecting area Angular resolution ~ /D
D Sensivity depends on collecting area Angular resolution ~ /D
VLA ALMA ESO VLTI
ARRAY Simple antenna “elements” “Station” “Array”
SKA Design “Magic Carpet”
Eggs on Legs
LOFAR = Low Frequency Array
on map of the Netherlands
10 arcmin LOFAR and SKA … Quasar distributed star formation
LOFAR and SKA … Z = log( neutral fraction ) Ciardi & Madau 2003