Light from the young galaxyâ€”captured by NASAâ€™s orbiting Spitzer and Hubble space telescopesâ€”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 â€œDark Ages.â€ 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.
â€œThis galaxy is the most distant object we have ever observed with high confidence,â€ 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.
â€œFuture work involving this galaxyâ€”as well as others like it that we hope to findâ€”will allow us to study the universeâ€™s earliest objects and how the Dark Ages ended,â€ adds Zheng.
Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASAâ€™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.
â€œIn essence, during the epoch of reionization, the lights came on in the universe,â€ says co-author Leonidas Moustakas, a research scientist at NASAâ€™s Jet Propulsion Laboratory, a division of the California Institute of Technology. …