Dusty, Distant Galaxy Looks Old in a Young Universe

Astronomers have made a somewhat unusual finding. They've found a galaxy that looks old, but exists in a young universe. The findings reveal a bit more about galaxy formation and tell them a bit more about the early universe.

The evolved system is one of the youngest and most remote galaxies ever found. Called A1689-zD1, the galaxy is observable only by virtue of its brightness being amplified more than nine times by a gravitational lens in the form of the galaxy cluster, Abell 1689. Astronomers can see this galaxy when the universe was only 700 million years old, which is only five percent of its present age.

What's interesting about the galaxy is that it's being observed as it was during the period of reionization, when the earliest stars brought the cosmic dawn. During this time period, these stars illuminated an immense and transparent universe and ended the "dark ages" of the universe.

"After confirming the galaxy's distance using the VLT, we realized it had previously been observed with ALMA," said Darach Watson, one of the researchers, in a news release. "We didn't expect to find much, but I can tell you we were all quite excited when we realized that not only had ALMA observed it, but that there was a clear detection. One of the main goals of the ALMA observatory was to find galaxies in the early Universe from their cold gas and dust emissions-and here we had it!"

The galaxy also looks unusual. Although researchers expected for it, like most young galaxies, to display a lack of heavier chemical elements, it actually possessed these elements. The galaxy emits a lot of radiation in the far infrared, indicating that it's already produced many stars and significant quantities of metals.

"This amazingly dusty galaxy seems to have been in a rush to make its first generations of stars," said Kirsten Knudsen, co-author of the new paper. "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."

The findings are published in the journal Nature.

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