GHOSTLY galaxies in the distant universe are almost certainly
the culprits behind reionisation, a change in intergalactic gas
that allows us to see across the cosmos. About 300,000 years
after the big bang, the charged hydrogen that filled the
universe became neutral and opaque, creating a cosmic fog that
blotted out visible light for a billion years. Then some form of
radiation broke up the hydrogen, reionising it and making it
clear. One theory says the radiation came from galaxies, but
Hubble's deepest view of the universe shows that bright galaxies
present during the reionisation era would not have been powerful
enough. Now statistical analysis shows there should be many
faint galaxies we can't yet see - enough to do the job, Matthew
Schenker of the California Institute of Technology said last
week at an astronomy meeting in California. - New Scientist -
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