About 10 years ago, astronomers catalogued a galaxy 12.4 billion light years away called COSMOS-AzTEC-1, a giant "monster galaxy" believed to be an ancestor of massive modern galaxies like ours. Galaxies go through an evolutionary process, changing from disordered masses of gasses to star-filled stunners like our own beautiful Milky Way. Because researchers are viewing AzTEC-1 at the early stages of its existence, they expected that it would still be a little chaotic. But Sarah Lewin at Space.com reports the galaxy might be ahead of the curve: the monster galaxy is producing 1,000 times as many stars as the Milky Way.
Researchers got a closer look at what's going on in this galaxy far, far, away using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a telescope that has 10 times greater resolution of previous telescope models. Essentially, AzTEC-1 looks more mature than it is, but looks can be deceiving. Lewin reports that while the galaxy is certainly more productive than expected for its age, it isn’t exactly a well-oiled, steady star-making machine. And while it’s not a total mess like they’d predicted either, it might not remain sustainable for very long.
“A real surprise is that this galaxy seen almost 13 billion years ago has a massive, ordered gas disk that is in regular rotation instead of what we had expected, which would have been some kind of a disordered train wreck that most theoretical studies had predicted,” study co-author Min Yun of the University of Massachusetts, Amherst, says in a statement.
In most galaxies, there is one dense cluster of star-forming gas in the center. AzTEC-1, however, has two off-center clouds thousands of light years from its galactic center that are also dense enough to produce stars, the team reports this week in the journal Nature.
There’s typically something of an equilibrium that keeps star-forming galaxies running smoothly. While gravity collapses masses of gas into new stars, dying stars explode into supernovae and push gas outward, thus creating a counterbalance that maintains the galaxy’s stability. The gravity in AzTEC-1, however, has the upperhand and compresses gas into stars at a runaway rate 1,000 times that of the Milky Way. At that pace, all the gas in the galaxy will be consumed in 100 million years, ten times faster than expected.
Exactly how AzTEC-1 became such a powerful star factory is hard to say. It’s possible that a galactic collision transported excess gas into the galaxy igniting intense star formation.
“How these galaxies have been able to amass such a large quantity of gas in the first place and then essentially turn the entire gas reserve into stars in the blink of an eye, cosmologically speaking, was a completely unknown question about which we could only speculate,” Yun says in the press release. “We have the first answers now."
This is not the only galaxy to challenge what we know about how the conglomerations of stars formed and evolved over the eons. Earlier this year, researchers found a galaxy that appears devoid of dark matter and in 2016 found galaxies made primarily of dark matter. And earlier this month researchers announced they’d discovered that some of the universe’s oldest galaxies, which are over 13 billion years old, may be pretty close to home, orbiting our own Milky Way galaxy.