“In our simulations, 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,” said Anglés-Alcázar.
The accepted theory of galactic formation is that shortly after the Big Bang, the hydrogen, helium and other trace elements started to clump together due to small density fluctuations, perhaps from dark matter that that provided the initial gravitational attraction. Matter then bunched together into larger and larger collections, forming the first proto-galaxies.
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Within these first galaxies, more clumps of material came together to eventually create the first stars. These stars lived short violent lives, ending in powerful supernovae that then seeded the next generations of stars. The first galaxies were gravitationally attracted to one other, and merged together into larger and larger structures, ultimately becoming the large spiral galaxies we know today.
But the intergalactic transfer of gas from other galaxies is “an important but previously under-appreciated growth mode,” the researchers said, emphasizing that their study showed that galactic winds are a “primary contributor to the baryonic mass budget of central galaxies.”
“This study transforms our understanding of how galaxies formed from the Big Bang,” Faucher-Giguère remarked in a statement. “What this new mode implies is that up to one-half of the atoms around us — including in the solar system, on Earth and in each one of us — comes not from our own galaxy but from other galaxies, up to one million light-years away.”
“Our origins are much less local than we previously thought,” he added. “This study gives us a sense of how things around us are connected to distant objects in the sky.”
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