Astroboffins peep at the largest orgy of galaxies banging into each other

The gargantuan blob could be creating the largest megastructure in the universe

gigantic_protocluster
Artist's impression of SPT2349-56. Image Credit: ESO/M. Kornmesser

Astronomers have spotted a whopping 14 galaxies on the verge of merging to create what could be the densest and most massive galactic cluster in the universe.

The discovery was made after the South Pole Telescope in Antarctica scanned the night sky and found a population of rare, extremely bright objects nicknamed SPT2349-56. Further analysis with the ALMA (Atacama Large Millimeter/submillimeter Array) revealed that it was a treasure trove of luminous galaxies almost piling on top of one another.

The results have been published in a paper in Nature on Wednesday. “That fact that we observed 14 star-bursting galaxies in this confined region of space was unexpected. It is way denser than anyone expected,” Tim Miller, lead-author of the study and an astronomy researcher at Yale University, told The Register.

It is estimated that each of these galaxies is spawning thousands of new stars every year, at a rate that is between 50 to 1000 times faster than the Milky Way. The level of high activity and redshift suggests that the blob of galaxies, described as a protocluster, was already at an advanced stage of formation when the universe was just 1.4 billion years old - about a tenth of the age that it is now.

Spiral

Comparisons with other ancient protoclusers shows that SPT2349-56 could be forming one of the most massive structures in the universe today. All 14 galaxies will eventually spiral into one another and merge to create one gigantic elliptical galaxy.

Miller estimated that the total mass of the elliptical galaxy would be about 100 billion solar masses. The researchers were pretty lucky to stumble across gigantic clusters like these, as it is unlikely that there are more than about 16 such objects across the entire sky.

In a separate study, another group of researchers report finding a similar mega protocluster made of ten galaxies.

“We learned that galaxy cluster formation happens much faster then expected,” said Miller. The team are planning further observations to probe how clusters and galaxies form in the early universe under extreme environments. ®

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