We all could be made of extragalactic space matter from supernova explosions


What even are we?

A collection of flesh, blood and bone —  or extragalactic matter spouted from supernova explosions in galaxies light years away?

Northwestern University researchers say it could be the latter in a surprising find that tweaks our understanding of the Big Bang Theory 14 billion years ago.

Using supercomputer simulations, the Northwestern team unexpectedly found that our galaxies gained their matter through intergalactic transfer, a recently identified phenomenon that took billions of years. Daniel Anglés-Alcázar, a postdoctoral fellow at Northwestern’s astrophysics center, explains it best.

“It is likely that much of the Milky Way’s matter was in other galaxies before it was kicked out by a powerful wind, traveled across intergalactic space and eventually found its new home in the Milky Way,” he said.

That means up to half of the Milky Way might be made of other galaxies. Meaning we, in part, could be formed from the same extragalactic matter. By our very nature, Anglés-Alcázar said, we’re “space travelers or extragalactic immigrants.”

To make the discovery, Anglés-Alcázar developed algorithms to track how galaxies gained matter. To do this, he used a program that produces 3-D models of galaxies and how they formed from the Big Bang to today.

After the Big Bang, researchers said, the universe was filled with gas, which by force of gravity, eventually formed stars and galaxies. The simulations found supernova explosions released gas, which caused atoms to be carried by galactic winds from one galaxy to another. Gas, researchers found, traveled from small galaxies to big galaxies, like the Milky Way, where it formed stars.

“We were able to trace the origins of stars in Milky Way-like galaxies and determine if the star formed from matter endemic to the galaxy itself or if it formed instead from gas previously contained in another galaxy,” Anglés-Alcázar said.

More than questioning our atomical makeup, the study published Wednesday in Monthly Notices of the Royal Astronomical Society could better explain how our galaxies evolved.

“Our origins are much less local than we previously thought,” said Northwestern professor Claude-André Faucher-Giguère, whose research team and others built the 3-D simulations. “This study gives us a sense of how things around us are connected to distant objects in the sky.”

The team at Northwestern will join with NASA’s Hubble Space Telescope to test intergalactic transfer predictions.