Ancient ‘Monster Galaxy’ Is Forming Stars a Thousand Times Faster Than the Milky Way

By Ryan F. Mandelbaum on at

Chile’s Atacama Large Millimetre/submillimetre Array (ALMA) has observed a galaxy that looks nothing like what researchers expected. It’s forming stars at an absolutely incredible rate.

The “Monster Galaxy”, also known as COSMOS-AzTEC-1, formed just 2 billion years after the Big Bang, and it turns more than a thousand Suns worth of gas into stars each year. Scientists still don’t understand these early galaxies very well, but now they have some new information that can shed light on why they form stars so blisteringly fast.

Essentially, the clumpy gas inside the galaxy has a stronger gravitational pull on itself than the force of the galaxy’s rotation or repulsion from stars and supernovae, according to the observations published today in Nature.

Scientists discovered galaxies like AzTEC-1 only two decades ago, according to the paper, and have studied them to try and understand extreme starburst events. By extreme, I mean the galaxy is forming stars a thousand times faster than the Milky Way does. These ancient galaxies are thought to be the ancestors of today’s elliptical galaxies, according to a press release.

An artist’s impression of AzTEC-1. Illustration: National Astronomical Observatory of Japan

The new team of researchers from Japan, Germany, Mexico and the United States observed AzTEC-1 at the highest resolution yet using ALMA’s 66 radio telescope dishes in the Chilean desert. The physicists looked for the signature of carbon monoxide gas inside the galaxy, and created a map of the galaxy based on what they saw.

Their observations revealed giant, dense clumps of gas which were concentrated enough that they were collapsing, rather than remaining stable from the outward pressure caused by star formation and supernovae. These collapsing clouds could form stars extremely quickly — and perhaps exhaust themselves in only 100 million years.

It’s still unclear how a galaxy can accumulate this much gas before beginning its period of crazy-fast star formation. Perhaps it’s the result of a galactic merger, though there isn’t evidence to support such a process yet. It will ultimately take observing other galaxies like AzTEC-1 to answer that question.

Things might seem pretty stable in our universe now. But never forget where you came from. Chaos reigns. [Nature]

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