Astronomers Just Spotted One Of The Oldest Galaxies We've Ever Seen

Zavala et al

Astronomers have found one of the oldest galaxies in the known universe, born just 1 billion years after the Big Bang.

Labelled HATLAS J090045.4+004125 or G09 83808, it was seen by the Large Millimeter Telescope (LMT) in Mexico as it appeared 12.8 billion years ago. This makes it the second oldest dusty galaxy we know of, and the oldest found by the LMT.

The discovery, published in Nature Astronomy, was led by Mexico’s National Institute of Astrophysics. The galaxy is going through an intense period of star formation, giving birth to about 380 solar masses worth of stars every year.

From this star formation rate, the astronomers were able to deduce that G09 is a member of the ultraluminous infrared galaxy (ULIRG) population. Only a handful of these galaxies are known of at such a great distance from us, as they are difficult to spot with optical telescopes like the Hubble Space Telescope.

“Seeing an object within the first billion years is remarkable because the universe was fully ionized, that is, it was too hot and too uniform to form anything for the first 400 million years,” Min Yun from the University of Massachusetts Amherst, one of the study’s co-authors, said in a statement.

“So our best guess is that the first stars and galaxies and black holes all formed within the first half a billion to 1 billion years. This new object is very close to being one of the first galaxies ever to form.”

The galaxy had first been spotted by the Herschel space telescope, but follow-up observations by the LMT helped get a better look at it. Astronomers made use of a gravitational lens to study it, when a huge galaxy passing between us and G09 bent and magnified its light towards us.

Finding a ULIRG galaxy like this helps us get a better look at the early galaxies in the universe. We’ve found other galaxies around this time going through extreme star formation of more than 1,000 solar masses a year. This type, however, may be more representative of the sorts of galaxies that populated the early universe.

“These sources may be more representative of the dusty star-forming galaxy population at these epochs than the extreme starbursts previously discovered,” the researchers wrote in their paper.

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