Our entire galaxy is warping, and a gigantic blob of dark matter could be to blame

A big blob of invisible darkish matter has bent our galaxy off form, a brand new examine suggests.

Scientists initially believed that the Milky Method was a flat disk dominated by two spiral arms trailing stars from a central bar, however measurements taken because the mid-Twentieth century reveal that it is bent inexplicably off form.

The warping happens principally at our galaxy’s borders, the place some areas bend downward whereas others flare upward — giving it the look of a crushed sombrero. Now, pc simulations might have revealed the trigger: a mysterious occasion that knocked our galaxy’s invisible halo of darkish matter out of alignment. The scientists printed their findings Sept. 14 within the journal Nature Astronomy.

Associated: Darkish matter may very well be build up inside lifeless stars — with probably explosive penalties

“These outcomes, together with information within the stellar halo, present compelling proof that our Galaxy is embedded in a tilted darkish matter halo,” the researchers wrote within the examine.

Darkish matter is a mysterious and considerably contradictory sort of matter. It makes up 85% of the universe’s matter; however as a result of it would not immediately work together with gentle, it’s fully invisible.

Nevertheless, scientists can observe its gravitational results on its environment. Darkish matter makes its presence recognized by accelerating stars to in any other case inexplicable speeds as they orbit galactic facilities; warping distant starlight; and by giving form to the Milky Method’s galactic halo.

The galactic halo — an enormous sphere of stars floating like leaves on a darkish matter pond — rests simply past the spiral arms of the Milky Method. In a 2022 examine, astronomers investigated this area utilizing the European House Company’s Gaia spacecraft, which maps the positions and actions of the Milky Method’s roughly 2 billion stars. By poring via Gaia’s information, they found that the celebrities suspended within the galactic halo have been surprisingly off-kilter.

To see what an unbalanced stellar halo would possibly imply for the darkish matter halo it’s suspended in, the researchers used a pc mannequin to recreate a younger Milky Method-like galaxy with a darkish matter halo tilted 25 levels with respect to its disk. After simulating the galaxy over 5 billion years, the researchers discovered that they’d created a really comparable galaxy to our personal.

“Right here we present {that a} darkish halo tilted in the identical path because the stellar halo can induce a warp and flare within the Galactic disk on the similar amplitude and orientation as the information,” the researchers wrote.

What brought about the darkish matter round our galaxy to fall out of tilt is not clear, however the researchers’ simulations counsel it’s more likely to have been a huge collision, doubtless from one other galaxy flying into our personal. This collision might have brought about the darkish matter halo to tilt up by as a lot as 50 levels earlier than slowly swinging all the way down to its present 20-degree angle elevation.

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