Astronomers have spotted what they say will soon become the most massive structure in the universe.
Peering into deep space — some 90% of the way across the universe, to be precise — the beginnings of a huge cosmic pileup, a collision of 14 galaxies, was observed.
This ancient smashup will eventually evolve into the most massive structure in the known universe: a gigantic galaxy cluster, held together by dark matter and swimming in a sea of hot, ionized gas.
The light from the galaxies began traveling to us some 12.4 billion years ago, when the universe was about a tenth of its current age. That was "only" about 1.5 billion years after the Big Bang, when the universe began.
"Having caught a massive galaxy cluster in throes of formation is spectacular in and of itself," said Scott Chapman, an astrophysicist at Dalhousie University in Halifax, Canada, who specializes in observational cosmology and studies the origins of structure in the universe and the evolution of galaxies.
"But, the fact that this is happening so early in the history of the universe poses a formidable challenge to our present-day understanding of the way structures form in the universe," he said.
What's also amazing, the astronomers said, is that the galaxies are forming stars as much as 1,000 times faster than stars form in our Milky Way.
This particular galactic protocluster, designated SPT2349-56, was first observed as a faint smudge in 2010 with the National Science Foundation's South Pole Telescope.
More detailed observations from powerful telescopes in Chile showed that the galaxies had unusual structure and confirmed that their light originated much earlier than expected — only 1.5 billion years after the Big Bang.
"How this assembly of galaxies got so big so fast is a mystery," said Tim Miller, a Ph.D. candidate at Yale University and lead author of the study. "It wasn’t built up gradually over billions of years, as astronomers might expect. This discovery provides a great opportunity to study how massive galaxies came together to build enormous galaxy clusters,” he said.
The study was published Wednesday in the peer-reviewed British journal Nature.