In what represents the first analysis of its kind, a team of astrophysicists at Northwestern University (USA) has discovered that up to half of the matter in our galaxy, the Milky Way, can come from distant galaxies. As a result, each of us could be made in part of extragalactic matter.
This conclusion is due to supercomputer simulations that identified a new phenomenon called intergalactic transfer, which could help us uncover the secrets of how galaxies evolve.
Simulations show that supernova explosions blow copious amounts of gas out of galaxies, causing atoms to be transported from one galaxy to another via powerful galactic winds.
“Since much of the matter we are made of may have come from other galaxies, we could consider ourselves space travelers or extragalactic immigrants. It is likely that much of that matter was in other galaxies before being blown away by a powerful wind, which it traveled through intergalactic space and finally found its new home in the Milky Way “, says Daniel Andamientos-Alcázar, leader of the study.
The galaxies are widely separated from each other , so even though galactic winds travel at several hundred kilometers per second, this process took place over several billion years.
For the study, the experts developed sophisticated numerical simulations that produced realistic 3D models of galaxies from the formation of a galaxy from the Big Bang to the present day; something that would require the equivalent of several million hours of continuous computing, quantifying how galaxies acquire matter from the universe.
By following in detail the complex flows of matter in the simulations, the research team found that gas flows from smaller galaxies to larger galaxies, such as the Milky Way, where the gas forms stars. This mass transfer through galactic winds can account for up to 50% of the matter in the largest galaxies.
The surprising thing is that the galactic winds contribute more material than we thought. “ It is a new mode of galaxy formation that we had not considered before . Up to half of the atoms that surround us – including in the solar system, on Earth and in each of us – do not come from our own galaxy, but from other galaxies, up to a million light years “, clarifies Angles-Alcázar.
And we already knew that material can move between galaxies, but we didn’t know how much.
After the Big Bang, 14,000 million years ago, the universe was filled with a uniform gas, without stars, without galaxies. But there were small disturbances in the gas, and these began to grow under the force of gravity, eventually forming stars and galaxies.
“ Our origins are much less local than we thought. This study gives us an idea of how things around us are connected to distant objects in the sky,” said Claude-André Faucher-Giguère, co-author of the work.
The findings open a new line of research to understand galaxy formation and the prediction of intergalactic transfer can now be tested. The Northwestern team plans to collaborate with observing astronomers who are working with the Hubble Space Telescope and ground-based observatories to test the simulation predictions.
Referencia: The Cosmic Baryon Cycle and Galaxy Mass Assembly in the FIRE Simulations arXiv:1610.08523 [astro-ph.GA] Monthly Notices of the Royal Astronomical Society. doi.org/10.1093/mnras/stx1517
