Scientists have long discovered that it is difficult to study the shape of a galaxy, in our case the Milky Way, when you live inside. Recently, however, the European space observatory Gaia has helped a lot with this, as it measures the positions of a large number of stars in the Milky Way in detail. Thanks to the Gaia observatory, astronomers have mapped the shape of our Galaxy in detail.
It turns out that the disk of the Milky Way is far from a regular geometric object. It is deformed and bent. Astrophysicist Jiwon Jesse Han from the American research center Harvard & Smithsonian Center for Astrophysics (CfA) and his colleagues are convinced that the culprit in this case is a huge mass of matter, which is, however, invisible to us.
According to them, the peculiar shape of the Milky Way disk has fingers of a galactic halo of dark matter, which they believe is displaced relative to the galactic disk.
Fears are not misplaced, apparently it is not a galactic disturbance with serious consequences. Nevertheless, it is of great interest to scientists, because the shape of the galactic disk and dark matter halo of the Milky Way contains information about the history of the Milky Way and its development.
Interacting with another galaxy?
Until now, the prevailing opinion among experts was that the curved disk of the Milky Way could be a direct result of an ancient or ongoing interaction with another galaxy. It’s no secret that the Milky Way is a seasoned galactic cannibal, having feasted on a number of smaller galaxies in the ancient and recent past.
Han et al. with they believe, that the effect of the “galactic collision” on the disk of the Milky Way was rather indirect. According to them, the collision of the Milky Way with another galaxy that occurred in the distant past led to a displacement of the dark matter halo.
Their simulations show that such a collision could shift the dark matter halo in a way that corresponds to the situation today, and that the consequences of such a shift were relatively quickly reflected in the shape of the Milky Way disk.
The simulations also indicated that after the aforementioned collision of galaxies, which may have occurred 7 billion years ago, the dark matter halo of the Milky Way was originally deflected much more, about twice as much as it is today. Since then, the inclination of the dark matter galactic hall of the Milky Way has been leveling back again.
2023-09-25 09:46:33
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