Scientists initially thought the Milky Way was a flat disk dominated by two spiral arms pulling stars from a central bar, but measurements taken since the mid-20th century showed it was inexplicably deformed. The warping occurs mainly at the edge of our galaxy, where some regions curve down while others flare up, making it look like a crushed sombrero. Now, computer simulations may have revealed the cause: a mysterious event that distorted our galaxy’s invisible dark matter halo. The scientists published their results on September 14 in the journal Nature Astronomy. Related: Dark matter can accumulate inside dead stars – with potentially explosive consequences. “These results, combined with stellar halo data, provide compelling evidence that our Galaxy is enveloped in a tilted halo of dark matter,” the researchers wrote in the report. learn.
Dark matter is a mysterious and somewhat contradictory type of matter. It represents 85% of the matter in the universe; but because it does not interact directly with light, it is completely invisible. However, scientists can observe its gravitational impact on the environment. Dark matter makes its presence known by accelerating stars to inexplicable speeds as they orbit galactic centers; distort the light of distant stars; and shaped the Milky Way’s galactic halo. The galactic halo – a giant sphere of stars floating like leaves on a pond of dark matter – lies just outside the Milky Way’s spiral arm. In a 2022 study, astronomers studied the region using the European Space Agency’s Gaia spacecraft, which mapped the positions and movements of about 2 billion star in the Milky Way. Looking through Gaia’s data, they discovered that the stars hanging in the galaxy’s halo were strangely misaligned.
To see what an unbalanced stellar halo might mean for the halo of dark matter in which it floats, researchers used computer modeling to recreate a young Milky Way-like galaxy with The dark matter halo is tilted 25 degrees relative to its disk. After simulating the galaxy for more than 5 billion years, researchers discovered that they had created a galaxy very similar to our own. “Here we show that a dark halo tilted in the same direction as the stellar halo can cause warping and rupture in the galactic disk with the same amplitude and direction as the data,” the researchers wrote. It’s unclear what causes dark matter to tilt around our galaxy, but researchers’ simulations suggest it could be a giant collision, possibly from another galaxy flying into our own. ta. This collision may have caused the dark matter halo to tilt up to 50 degrees before slowly lowering to its current elevation angle of 20 degrees.