This Ancient Galaxy Cluster Formed Just 1.5 Billion Years After the Big Bang

Thursday, 26 April 2018 - 7:54PM
Space
Space Imagery
Astronomy
Thursday, 26 April 2018 - 7:54PM
This Ancient Galaxy Cluster Formed Just 1.5 Billion Years After the Big Bang
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ESO/M. Kornmesser
The early universe is still in many ways a mystery, but we do have some idea of what it looks like thanks to light from distant galaxies

And SPT2349-56, a galactic protocluster sitting at 12.4 billion lightyears away beyond 90 percent of the observable universe, is certainly distant. According to the European Southern Observatory, team of researchers just picked up traces of this distant cosmic gathering, providing a crucial look at how the universe looked when it was just a tenth of its current age (the universe is thought to be around 13.8 billion years old). 

The galaxies were discovered using two highly advanced telescopes at the ESO, the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX). Both are designed to look at extremely distant and cold cosmic objects, which is why the researchers were startled by the surprisingly dense group of galaxies here.

After all, the scientific consensus was that an enormous galaxy cluster (or protocluster) like this one would take much longer to form, but the universe had managed to start putting some together at a fairly young age. 



The term "protocluster" is mostly used because "galactic cluster" has a specific meaning beyond just a cluster of galaxies - to qualify as a galaxy cluster, one of the largest structures in the universe, it would have to be 10^14–10^15 solar masses and the galaxies would have to be completely bound together by gravity. This protocluster full of starburst galaxies is on track to become just that, but it hasn't had much time at such an early stage despite how fast it was progressing.

According to Tim Miller, the leader of the research team that made the discovery (and not the same Tim Miller who directed Deadpool and the upcoming Neuromancer film), this provides a great opportunity to look into how early galaxies formed. He said the following in an official press release from the ESO:

Opening quote
"How this assembly of galaxies got so big so fast is a mystery. 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."
Closing quote


It's thought that major structures like this are held together through dark matter, which was present in the universe's earliest stages. But while dark matter is still extremely difficult to study, enormous and distant galaxies are slightly easier.
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