Most distant galaxy shines light on early universe

By | September 21, 2012

Most distant galaxy shines light on early universe

Light from the young galaxy—captured by NASA’s orbiting Spitzer and Hubble space telescopes—started its sojourn toward Earth when the now-13.7-billion-year-old universe was just 500 million years old.

The far-off galaxy is seen as it existed during an important period, when the universe began to transit out of its so-called “Dark Ages.†During this period, the universe went from a dark, starless expanse to a recognizable cosmos full of galaxies.

The discovery of the faint, small galaxy opens up a window into the deepest, remotest epochs of cosmic history.

“This galaxy is the most distant object we have ever observed with high confidence,†says Wei Zheng, a principal research scientist in physics and astronomy at the Johns Hopkins University and lead author of a paper appearing in Nature on Sept. 20.

“Future work involving this galaxy—as well as others like it that we hope to find—will allow us to study the universe’s earliest objects and how the Dark Ages ended,†adds Zheng.

Five wavebands

Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA’s telescopes. In other words, the starlight snagged by Spitzer and Hubble left the galaxy when the universe was just 3.6 percent of its present age.

Unlike previous detections of possible galaxies in this age range, which were only glimpsed in a single color, or waveband, this newfound galaxy has been seen in five different wavebands. …

About 400,000 years after the Big Bang, neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies, however, did not emerge until a few hundred million years later.

The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, the state in which the gas has remained since that time.

“In essence, during the epoch of reionization, the lights came on in the universe,†says co-author Leonidas Moustakas, a research scientist at NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology. …

via Futurity.org – Most distant galaxy shines light on early universe.

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