Half of Our Galaxy Might Have Come From Other Galaxies
It turns out that, if new estimates are right, half of the atoms in our galaxy could have been stolen from other galaxies. The new analysis, from a team of astrophysicists from the United States and Canada, shows that galaxy formation (and the formation of stuff in general) is a complex give-and-take process.
"Overall, our results highlight the role of
"The question of how much of the Milky Way's stars were built up "in place", versus acquired from other sources, "has always been an intriguing one," astrophysicist Dylan Nelson from the Max Planck Institute for
The authors cite papers as far back as 2003 describing the importance of the exchange of matter in galaxy formation, but including it in models has been quite difficult due to certain smaller-scale physical complexities. But a simulation called Feedback In Realistic Environments (FIRE) helped these researchers come up with a way to model the behavior of gasses in and between galaxies.
The researchers took into account things like star formation, supernovae, stellar winds, and other factors to model galaxies and their galactic winds. Their simulation then put a main galaxy in the center of others, and played the system in reverse. After lots of number crunching and supercomputing, the researchers found that only 50 percent or so of the stuff in a Milky Way-type galaxy at present came from internal processes, like star formation and sucking up previously-ejected galactic winds. The rest came from other galaxies.
Of course, this was just a simulation. But at least one outside researcher,
at the University of Washington in Seattle,
New Scientist that the work included "one of the best simulations." She pointed out that understanding where the atoms in the Milky Way come from is an important topic in astrophysics.
Nelson did point out that the model only looks at three simulated galaxies like the Milky Way, and it arrives at between 30 and 60 percent external stuff. "It's unclear if our real MW corresponds closely to any, or which, of these particular simulations. A much larger number of simulated galaxies (as we attempt to do in projects such as www.tng-project.org ) would be needed to pin down the importance and frequency of the effect described in this work." But he agreed the model was a sophisticated one, and told Gizmodo the work was "undoubtedly roughly correct."
And who knows, maybe in a few billion years time, someone else's body will be made out of your atoms. That would be nice.
[ MNRAS ]