Toronto — The oldest, largest galaxies in the universe once lived fast and furiously, forming stars in a remarkably short time, according to astronomers. But about three billion years after the Big Bang, they applied the brakes and the growth of these galaxies stopped.

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“Right after the Big Bang 14 billion years ago, the most massive galaxy in our universe formed incredibly quickly,” said Kate Whitaker, a professor of astronomy at the University of Massachusetts Amherst. News release. “But for some reason, they’ve stopped. They’re not making new stars anymore.”

It’s a mystery that has puzzled experts until now.

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It turns out that these galaxies are running out of cold gas needed to form new stars.

In one discovery Published Wednesday in the journal Nature, astronomers observed some of these ancient, distant galaxies. These galaxies are so far away that we’re only seeing light emitted from 10 to 12 billion years ago, which is when the universe was in its infancy.

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In fact, it is a look into the deep past.

“The early universe contained abundant cold gas, so these galaxies from 12 billion years ago must have had a lot left in the fuel tank,” Whitaker said.

But, it turns out that is not the case.

Whitaker’s team combined images from the Hubble Space Telescope and readings from the Atacama Large Millimeter/submillimeter Array, which detects radiation invisible to the naked eye, detected only the amount of cold molecular gas at the center of these galaxies .

This means that these galaxies either burned through their energy supply or pushed them out within the first few billion years of the universe’s existence, according to the researchers. It also raises the possibility that each galaxy may have some impediment to its replenishment of cold gas.

Next, the research group intends to investigate how dense the remaining cold gas is in these dormant and dormant galaxies and why it is only present at the center of these galaxies.