Milky Way: Smaller galaxies flying past can cause structural changes, say Indian astronomers

While the universe is constantly expanding and not showing any signs of slowing down, galaxies collide or pass close to each other in galactic flybys all the time.

Scientists have consensus that there will come a time when all galaxies are too far away to even be visible from Earth. But currently, several of them are moving towards each other. Some are on collision course like the neighbouring Andromeda, while some other smaller satellite galaxies are expected to flyby close enough to impact our home galaxy Milky Way, known in Hindi as Akashganga.

Research has been ongoing globally to understand the impact of such galactic flybys. A study by Indian astronomers has revealed that such flybys of smaller galaxies can cause major disruptions to the Milky Way.

As per the latest study published in the journal Monthly Notices of Royal Astronomical Society, a smaller galaxy flying past a larger one like the Milky Way can lead to significant disruptive changes to its structure. The astronomers concluded that such passage of smaller galaxies can initiate the creation of new spiral arms in larger spiral-shaped galaxies like the Milky Way.

.@IIABengaluru #astronomers revealed that when a smaller galaxy flies past a much larger galaxy like our own #milkyway ,it can trigger formation of spiral arms in larger galaxy, thereby changing its structure.@DrJitendraSingh @RenuSwarup @fiddlingstars
https://t.co/P4gEYlINip pic.twitter.com/4cXNG2zCbw

— DSTIndia (@IndiaDST) October 12, 2021

The astronomers analysed the impact of such ‘minor flybys’ on the discs, bulges and spiral arms of galaxies similar sized to our Milky Way. One disruption leads to the thickening of discs of the bigger galaxies.

They further state that such flybys are common and significant for galactic evolution. Such incidences result in the exchange of mass and energy in vast amounts. The structures, the astronomers stated, can fade away in time, highlighting the importance of the study.

While galactic collisions result in two galaxies merging to form a bigger one, like the predicted Milkdromeda which will result out of the merger of our Milky Way with neighbouring Andromeda. On the other hand, galactic flybys do not result in merger of two galaxies, but do put tremendous gravitational force before passing by.

The research was based on simulations using powerful supercomputers to note the structural changes due to the immense gravitational pull of flybys.