Cosmic Giant Meets Galactic Dwarf: What Happens When Galaxies Collide

What happens when two galaxies smash together? That's a good question. Now, scientists have taken a closer look at what happens when a galactic giant crashes into a cosmic dwarf.

Previously, researchers thought that when two galaxies smash into each other their gas clouds get churned up and seed the birth of new stars at a much faster rate than if they had remained separate. In this latest study, though, scientists have pointed out that this idea is too simplistic.

In this latest study, the scientists used the Galaxy and Mass Assembly (GAMA) survey observed using the Anglo-Australian Telescope in regional New South Wales. They found that whether a galaxy forms stars more rapidly in a collision or forms any new stars at all depends on if it is the bigger or smaller galaxy in a galactic collision.

"When two galaxies of similar mass collide, they both increase their stellar birth rate," said Luke Davies, one of the researchers, in a news release. "However when one galaxy significantly outweighs the other, we have found that star formation rates are affected for both, just in different ways. The more massive galaxy begins rapidly forming new stars, whereas the smaller galaxy suddenly struggles to make any at all."

The findings reveal a bit more about what happens when galaxies collide. This, in particular, is important to note when it comes to our own Milky Way galaxy and the nearby Andromeda galaxy. Because the pair are like cosmic tanks, both of similar size, they will begin to affect one another's star formation as they get closer. Eventually, they will merge to become a new galaxy.

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.

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