Recent observations show that galactic merging processes were already happening at 1.5 billion years after the Big Bang, twice as fast as expected. This is an amazing discovery that astrophysics doesn’t yet know how to explain. Thanks to the ALMA and APEX telescopes’ observations, two scientific teams, one American and one British, have discovered very dense concentrations of galaxies on the position of forming the so-called galaxy megamergers, some gigantic galactic clusters.
The findings change the theories regarding the period of formation of gigantic galactic cluster
If these phenomena are not in intrinsically astonishing, it is the period in which they occurred that puzzles the astronomers. These objects formed when the Universe was only 1.5-billion-year old.
Until now, scientists thought that this type of events occurred much later, around 3 billion years after the Big Bang.
The US team, led by Tim Miller a professor at the Dalhousie University, in Canada, and the Yale University, in the US, identified a protocluster of 14 massive galaxies, while the British team led by Ivan Oteo, of the University of Edinburgh, had already uncovered 10 similar galaxy megamergers.
“These discoveries from ALMA are just the tip of the iceberg. Additional observations using the APEX telescope show that the actual number of star-forming galaxies is likely to be three times higher. Another observation campaign currently being carried out with the MUSE instrument, installed on the ESO’s VLT, is also leading to the identification of other galaxies”, notes Carlos De Breuck, ESO astronomer.
Ivan Oteo explained that these objects were supposed to be rare
The scientist said that the visible lifespan of such objects was considered relatively short because they consume their gas at an extraordinarily high rate but the computer models forecast that the time needed for these massive protoclusters is longer than the prior observations suggested.
The process responsible for the rapid merge of such a number of galaxies is still a mystery for researchers.
“This cluster has not built up gradually over billions of years, contrary to what astronomers thought. This discovery provides a great opportunity to study how massive galaxies have come together to form gigantic galactic clusters,” said Tim Miller discussing the observations on these galaxy megamergers, which are still puzzling the astronomers, conducted with the ALMA and APEX telescopes.