Old and Dusty Galaxies Grew Up Stunningly Fast, Say Experts

Researchers have discovered that soon after the Big Bang, some of the first galaxies may have been in a rush to make stars. That's at least the case for A1689-zD1, an ancient galaxy that's an incredibly long way from Earth - so far away that we are seeing it from when the Universe was a mere 700 million years old.

You're probably familiar with the concept of light-years. Some stars and other celestial bodies are so far away from Earth that it even takes their light millions, if not billions of Earth years to reach our planet. That's why some of the stars we see in the sky may have long since disappeared, and what we are seeing is actually more like a recap of the Universe's history.

That's the case for the light from A1689- zD1, which is only reaching us now with the help of the gravitational magnification from a spectacularly dense and massive (and far younger) galaxy cluster known as Abell 1689.

Light from A1689- zD1 was first noticed by astronomers using the Hubble Space Telescope some time ago. And based on its position near what is reportedly the oldest part of the Universe, it was long thought to have been one of the very first galaxies ever formed, helping usher out a time called the stellar Dark Ages when no stars existed. (Scroll to read on...)

Using state-of-the-art equipment like the European Southern Observatory's Very Large Telescope and the Atacama Large Millimeter/submillimeter Array, researchers were able to properly see this ancient galaxy for the first time.

The light they were seeing was estimated to actually be 13.1 billion years old - meaning that the Universe was only 700 million years old when A1689- zD1 existed.

And yet, even if that's young for the Universe, the galaxy itself surprised astronomers by looking very old.

As a "cosmic infant," A1689- zD1 was expected to display a lack of heavy metals and other chemicals - which are often only produced after several generations of stars live out their entire lives in a galaxy. Instead, A1689-zD1 seemed to be emitting a lot of radiation in the far infrared, indicating that it had already produced many of its stars and significant quantities of metals. It also was chock full of dust and gas, boasting ratios of both materials similar to what "modern" galaxies have in their later lives.

Still, astronomers are convinced that the galaxy wasn't born earlier than they thought. Instead, a harsh childhood may have simply matured A1689-zD1 faster than expected. The team suggests that the conditions of the Universe soon after the Dark Ages were simply very different than thought, promoting fast galactic aging in a die-or-shine kind of world.

"Although the exact origin of galactic dust remains obscure our findings indicate that its production occurs very rapidly, within only 500 million years of the beginning of star formation in the Universe," research lead Darach Watson, of the University of Copenhagen, explained in a statement. "[That's] a very short cosmological time frame, given that most stars live for billions of years."

"This amazingly dusty galaxy seems to have been in a rush to make its first generations of stars," added co-author Kirsten Knudsen, of Chalmers University of Technology. "In the future, ALMA will be able to help us to find more galaxies like this, and learn just what makes them so keen to grow up."

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