Cosmic tsunamis or collisions between numerous galactic clusters releases immense amount of energy which can revive "dead galaxies." The revival may be temporary in some cases.
Researchers at the Leiden Observatory and University of Lisbon analyzed the data from the merging galaxy cluster CIZA J2242.8+5301. They saw that the humungous amount of energy which was subsequently produced was enough to make a few dead galaxies alive again.
They said that, "Galaxy clusters are like cities, where thousands of galaxies can be packed together, at least in comparison to the sparsely-populated space around them. Over billions of years, they build up structure in the universe - merging with adjacent clusters, like growing cities absorb nearby towns. When this happens, there is a huge release of energy as the clusters collide," according to a statement from the group released to Royal Astronomical Society.
Dead galaxies are those galaxies, which have used up all their energy and are dead. When their energy is used up then they also do not form any new stars.
"Sausage" or CIZA J2242.8+5301 is situated more than two billion light years away from Earth. It is located in the northern hemisphere, adjacent to Lacerta's constellation.
Andra Stroe of the Leiden Observatory said that they expected that the dead galaxies wouldn't have any kind of role in the cosmic tsunami but they were shocked to see that they are the main protagonists.
The dead galaxies in "Sausage" are springing back to life and they are also forming stars at an exponential rate, amply proving that they are alive again, according to Nat Monitor.
During the cosmic tsunami, high-density cold gas clouds are also formed which are very essential to the existence of the newly formed stars.