Scientists Solve Mystery of Star Formation from Collision of Two Galaxies

A team of astrophysicists have untangled the mystery of starburst galaxies - the formation of stars that takes place when two galaxies collide.

When the gas inside the galaxies gets dense enough to collapse a star is formed. During the galactic merging the rise in the random motion of the gas producing turbulence should obstruct the collapse of gas. When this occurs spontaneously the turbulence should either be slow or shut the formation of stars. But the astronomers noticed that the opposite of this takes place.

The mystery behind this has finally been decoded by a team of French astrophysicists at Florent Renaud of the AIM institute, Paris.  They provided an explanation using state of the art computer simulations.   This novel simulation was made using Europe's two most powerful supercomputers. They successfully modeled a galaxy similar to the Milky Way and the two colliding Antennae galaxies.

 Though not different from a separate class of galaxy, the starburst galaxies are known to display some special properties.  They are the galaxies that form stars at an extraordinarily fast rate. They are known to create powerful galactic winds that influence the future star formation. When compared to the rate of star formation in normal spiral galaxies, the rate of star formation in a starburst galaxy is 10-100 times much greater.

Using 12 million hours of time on the Supercomputer Curie, the team modeled a galaxy based on the Milky Way to replicate conditions across 300,000 light years.

The supercomputer SuperMUC was used for Antennae type galaxy, and simulated a volume of gas 600,000 million light years wide. Putting in millions of computational time, the team was able to recreate the model with every detail in it involving the random motion of gas inside the galactic disk.

According to Phys.Org, "By simulating the impact of the Antennae collision and merger on material 1000 times less massive than anything attempted before and comparing this with the Milky Way model, Florent and his team were able to demonstrate that the collision changes the nature of the turbulence in the galactic gas."

They noticed that the gas instead of whirling around enters a state where it is more likely to be compressed. Hence, when the galactic merging takes place an excess of dense gas that collapses into the star is produced and both galaxies experience a starburst.

Florent comments: "This is a big step forward in our understanding of star formation, something only made possible by the similarly major and parallel advances in computing power. These systems are helping us unlock the nature of galaxies and their contents in ever more detail, helping astronomers to slowly assemble their complete history."

The finding was documented in journal Monthly Notices of the Royal Astronomical Society.