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Nearby galaxy might explain what tore apart universe’s hydrogen

Radiation from star cluster hints at what caused epoch of reionization after the Big Bang

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9:03am, October 10, 2014
galaxy in UV light

RADIANT GLOW  Ultraviolet light (orange) pours out of a galaxy in this image from NASA’s GALEX satellite. New Hubble observations reveal this galaxy might mimic the earliest galaxies in the universe.

A nearby galaxy is leaking clues about one of the biggest makeovers in the history of the universe. New observations show that tiny galaxies in the early universe could have triggered the epoch of reionization — a period when harsh radiation tore apart hydrogen atoms — which astronomers consider key to understanding how stars and galaxies arose from the universe’s early dark void.

“Reionization is one of the major milestones in the universe’s history,” says Brant Robertson, an astronomer at the University of Arizona in Tucson. In the cosmic dark ages, neutral hydrogen gas filled the universe. Then, sometime within a billion years after the Big Bang, ultraviolet radiation filled the universe and ripped electrons from all the hydrogen atoms, leaving them ionized. Astronomers suspect that the radiation came from intense bursts of star formation in the first generations of galaxies.

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