Two teams of astronomers have used the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX), in Chile, to observe dense concentrations of so-called “starburst” galaxies.
With these galaxies packing together so closely, the scientific teams realized that they were getting ready to violently collide and merge with each other, which would eventually produce gigantic galaxy clusters.
One of the two teams was led by Tim Miller from Yale University.
His team used ALMA to peer back some 12.42 billion years in time, or when the universe was only 1.4 billion years old, to watch the early stages of a massive cosmic pileup.
What Miller’s team found was a galaxy protocluster of 14 “starburst” galaxies named SPT2349-56.
Each of these individual “starburst” galaxies was found to be quite prolific and were spitting out stars some 1,000 times faster than the Milky Way in an area of space that is only three times the size of our home galaxy.
It’s thought that the forthcoming mammoth galaxy cluster could eventually become one of the biggest structures in the known universe.
Miller wondered how the observed grouping of galaxies was able to grow so fast was a mystery. “It wasn’t built up gradually over billions of years, as astronomers might expect,” he said in a press release from the National Radio Astronomy Observatory (NRAO).
“This discovery provides an incredible opportunity to study how galaxy clusters and their massive galaxies came together in these extreme environments,” he added.
A study outlining the Miller team’s findings was published in the journal Nature.
Iván Oteo, who is with the European Southern Observatory (ESO), led the other team of astronomers in finding another megamerger similar to Miller’s.
The collection of 10 dusty “starburst” galaxies, discovered by his team, was given a nickname of a “dusty red core” because it was very red in color.
The galaxies in Oteo’s megamerger were first seen by the South Pole Telescope and the European Space Agency’s Herschel Space Observatory as dim blotches of light.
The team then used ALMA and APEX to determine the merger’s odd structure and to confirm that its light began traveling through the universe about 1.5 billion years after the Big Bang.
“The lifetime of dusty starbursts is thought to be relatively short, because they consume their gas at an extraordinary rate, explained Oteo in a press release from the European Southern Observatory (ESO).
“At any time, in any corner of the Universe, these galaxies are usually in the minority. So, finding numerous dusty starbursts shining at the same time like this is very puzzling, and something that we still need to understand,” he added.
The findings of the Oteo team’s research were detailed in a recent study published in the Astrophysical Journal.