Early Growth of Giant, Bright Galaxy Spotted Just 3 Billion Years After the Big Bang

Astronomers may have just caught the first glimpse of the earliest stages of galaxy construction. They've spotted a building site, nicknamed "Sparky," that is a developing galaxy containing a dense core blazing with the light of millions of newborn stars.

The researchers first spotted the infant galaxy with the help of NASA's Hubble and Spitzer space telescopes, the European Space Agency's Herschel Space Observatory and the W.M. Keck Observatory. Because the galaxy is so far away, it is seen as it appeared about 11 billion years ago, which is just 3 billion years after the birth of our universe. It's likely that this galaxy will continue to grow and perhaps even become a giant elliptical galaxy

"We really hadn't seen a formation process that could create things that are this dense," said Erica Nelson, one of the researchers, in a news release. "We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore."

The tiny galaxy already contains about twice as many stars as our own galaxy, crammed into a region about 6,000 light-years across. It's very possible that this galaxy may be representative of a much larger population of similar objects that are obscured by dust.

"They're very extreme environments," said Nelson. "It's like a medieval cauldron forging stars. There's a lot of turbulence, and it's bubbling. If you were in there, the night sky would be bright with young stars, and there would be a lot of dust, gas, and remnants of exploding stars. To actually see this happening is fascinating."

The massive amount of star formation is likely due to the fact that the galactic center is forming deep inside a gravitational well of dark matter, which is matter that makes up the scaffolding upon which galaxies formed in the early universe. Currently, a torrent of gas is flowing into this well at the galaxy's core, sparking waves of star birth.

It's likely that the galaxy has been furiously making stars for more than a billion years. Yet the galaxy didn't keep up this pace for long and eventually stopped forming stars in the packed core. Smaller galaxies then may have emerged with the growing galaxy.

"I think our discovery settles the question of whether this mode of building galaxies actually happened or not," said Pieter van Dokkum, one of the researchers. "The question now is, how often did this occur?"

The findings are published in the journal Nature.