It’s a dog eat dog universe—new archaeological surveys by researchers into the Andromeda galaxy proves the theory of galaxy formation through the destruction of others. 

Upon hearing the word archaeology, space isn’t normally the first thing that comes to mind. Yet, the Pan-Andromeda Archaeological Survey (PAndAS) is changing not only the semantics of the word, but also the way we think about galaxy formation.

The project, currently halfway complete, uses the Canada-France-Hawaii Telescope to get a closer look on our nearest big galaxy, Andromeda (about two million light years away). “It’s a small telescope, but it has a very wide field imaging camera that photographs one square degree of the sky, which is about a few times bigger than a full moon,” said UBC astronomy professor Harvey Richer, one of the researchers involved in the international project. 

“What we are doing is taking images of the area around Andromeda and what we have found is that the galaxy extends far further out than any had previously thought. What we are seeing is the splash of the interaction between two galaxies (Andromeda and its companion, the Triangulum galaxy), spread all around it, which is quite spectacular,” said Richer.

“Basically, Andromeda has cannibalized the galaxies it comes into contact with.”

As Richer explained, these findings are very important in proving the so-called “hierarchal galaxy formation theory,” which states that galaxies grow by interaction with other galaxies. “Up until now, it was a nice theory, but these findings provide a smoking gun for it,” he said. “Through PAndAs, we can see, virtually in real time, one galaxy being torn apart and its stars splashed all over the place.”

It is not only the Andromeda galaxy that is less than neighbourly—our own Milky Way is doing the same. “We see the Sagittarius galaxy, which is quite big, being ripped apart by our galaxy. It happens all the time. Even the Milky Way and Andromeda are moving towards each other. In about five to six billion years, the Milky Way will be torn apart by Andromeda and there will just be one big elliptical galaxy left in our local group,” Richer explained.

The PAndAS project has currently charted half of the Andromeda galaxy and is hopeful that it will complete the other half in its remaining one and half years left, finding new evidence of smaller galaxies being eating alive by Andromeda in the process.