Milky Way from the International Space Station (NASA/Reid Wiseman)


  • Galaxies are systems of star clusters, stardust, interstellar dust and even dark matter in the Universe (Bradac et al. 2006). Our Solar System for example resides in the Milky Way galaxy about 26000 light years away from the galactic center (Eisenhauer et al. 2003).
  • A recent research from the Northwestern University suggests that galaxies might exchange their galactic matter during extreme violent explosions (Anglés-Alcázar et al. 2017). This result would have very interesting implications on the origin of our Milky Way and ultimately of our Solar System.     

In order to get a better insight on the mechanisms of structure formations in the Universe and how they evolve with time it is important for us to know how galaxies are formed. Up to date, it is not completely understood how the matter in a galaxy comes together to form the galaxy bulk but a research group from the Northwestern University has recently found that 20%-60% of the mass in Milky Way –like (of the same mass as Milky Way) galaxies may have come from other neighboring galaxies via huge intergalactic winds (Anglés-Alcázar et al. 2017). Their findings show that the gas produced during gigantic supernovae is blown away and then nabbed by other galaxies. This gas is the building block for all the star formation in a galaxy and thus, it is crucial to know whether it is always recycled within a galaxy or if it migrates in the intergalactic space as this research indicates.

The group has used the “Feedback in Realistic Environments” (FIRE) simulations (Hopkins et al. 2014) to model clusters of galaxies. The FIRE domain allows for initial input parameters such as the metal content according to stellar population synthesis model, which is a model that uses the fact that galaxies are made of stars and dust (Leitherer et al. 1999). The very high resolution of FIRE (Anglés-Alcázar et al. 2017) has allowed physicists to track the creation and disruption of enormous molecular clouds, and finally determine how the matter moves within a galaxy and between galaxies. 

This finding would help us better understand the birth and the evolution of our Milky Way galaxy. Before, scientists had thought that the galaxies were formed not long after the Big Bang, and the galactic matter would always stay inside a galaxy even during some of the most aggressive astronomical occurrences such as supernova explosions (Reynolds et al. 2008). Instead these results imply that the Milky Way might have been formed and grown merely by swiping gas from nearby galaxies.  


COPYRIGHT: This article is the property of We Speak Science, a nonprofit institution co-founded by Dr. Detina Zalli (Harvard University) and Dr. Argita Zalli (Imperial College London). The article is written by Bianka Mecaj, MSc in Physics ETH Zurich-Ecole Polytechnique, Paris.