Feb. 5 (UPI) -- Astronomers have found a rare giant galaxy in the distant, or early, universe.
Scientists found the galaxy, situated 12 billion light-years away, using the W. M. Keck Observatory, a pair of powerful telescopes on the summit of Maunakea, a dormant volcano on the island of Hawaii.
When scientists use powerful telescopes to observe the most distant light in the universe, they're seeing the cosmos as it was billions of years ago, which is why the distant universe is also called the early universe.
Scientists were surprised to find such a massive galaxy in the early universe. Images of the newly found galaxy, dubbed XMM-2599, allowed scientists to study the universe as it was when it was only 1.8 billion years old.
"Even before the universe was 2 billion years old, XMM-2599 had already formed a mass of more than 300 billion suns, making it an ultramassive galaxy," lead study author Benjamin Forrest, a postdoctoral researcher in department of physics and astronomy at the University of California, Riverside, said in a news release.
But the monstrous galaxy wasn't just massive. It was also dormant.
"More remarkably, we show that XMM-2599 formed most of its stars in a huge frenzy when the universe was less than 1 billion years old, and then became inactive by the time the universe was only 1.8 billion years old."
Astronomers were able to accurately measure the distance of XMM-2599 using the observatory's Multi-Object Spectrograph for Infrared Exploration. The team of researchers published their observations this week in Astrophysical Journal Letters.
"It's exciting to see one of our most in-demand instruments successfully characterize such a rare, ancient galaxy with a short life span," said study co-author Percy Gomez, an astronomer at Keck Observatory. "It took many hours-long observations, some as much as nine hours each, to determine XMM-2599's distance and mass."
Though massive galaxies in the early universe are rare, cosmological models do predict their presence. However, most simulations produce massive galaxies that are still forming stars.
"What makes XMM-2599 so interesting, unusual, and surprising is that it is no longer forming stars, perhaps because it stopped getting fuel or its black hole began to turn on," said Gillian Wilson, a professor of physics and astronomy at Riverside. "Our results call for changes in how models turn off star formation in early galaxies."
Scientists aren't sure why the massive galaxy is currently inactive. It's possible the galaxy ran out of stellar fuel, or the birth of a supermassive black hole resulted in the depletion of the galaxy's gas and dust supply. Through continued monitoring of XMM-2599 and its surroundings, astronomers hope to better understand how such a galaxy might behave as it evolves.
"Perhaps during the following 11.7 billion years of cosmic history, XMM-2599 will become the central member of one of the brightest and most massive clusters of galaxies in the local universe," said study co-author Michael Cooper, a professor of astronomy at the University of California, Irvine. "Alternatively, it could continue to exist in isolation. Or we could have a scenario that lies between these two outcomes."
