Are we 'immigrants' in our own galaxy? Understanding intergalactic transfer

Where do we come from? It is the age-old question. How exactly was our planet formed? Now thanks to a groundbreaking study we have a better idea.

"So we run a set of high-resolution cosmological simulations which allow us to follow the formation of galaxies from early after the Big Bang and all the way down to the present day," said Dr. Daniel Angles-Alcazar.

He and his team at Northwestern University used supercomputer simulations to explore the evolution of galaxies. What they discovered was amazing. The newly understood phenomenon is called "intergalactic transfer."

"What we found out is that these galactic winds are actually connecting galaxies and are tranferring a significant amount of material between galaxies, which was quite a surprising result for us," Angles-Alcazar said.

Dr. Mordecai-Mark Mac Low is the curator of astrophysics at the American Museum of Natural History.

"What's remarkable about this study is that it showed that many of those stars weren't even in our own galaxy," he said.

In effect our galaxy, the Milky Way, "borrowed" from other galaxies. Supernova explosions inside one galaxy transmit gas and material that end up in another galaxy.  

"Galaxies don't grow apart from each other in isolation," Mac Low said. "Instead, they're constantly interacting with each other and trading material back and forth."

What this all means, believe it or not, is that you and I may be part alien.

"Perhaps we would even consider ourselves that we are immigrants in our own galaxy," Angles-Alcazar said. "Or at least in terms of the origin of the atoms that we are made of."

Mac Low said, "This continues to confirm our understanding that the physics that we see here on earth is the same as the physics we see halfway across the universe."

But the intergalactic transfer doesn't exactly happen overnight.

"So even traveling at very high velocities -- hundreds of kilometers per second, hundreds of miles per second -- it still takes billions of years to actually travel these enormous distances," Mac Low said.

So while we continue to search for answers here on earth, a lot of what we already know is from a galaxy far, far, away.

To help understand how complex this study was, consider this -- the Northwestern team needed several million hours of continuous computing to reach their findings.