Discovered a mechanism that explains the existence of galaxies without dark matter

(ORDO NEWS) — In a new study, an international team of astronomers report that when tiny galaxies collide with larger galaxies, those large galaxies can pull all the dark matter from smaller galaxies.

We cannot see dark matter directly, but astrophysicists believe that it exists because without its gravitational influence, we cannot explain the movement of stars in galaxies.

This new mechanism could explain the existence of galaxies without dark matter, a version that previously seemed impossible.

It all started in 2018, when astrophysicists Shany Danieli of Princeton University and Pieter van Dokkum of Yale University observed two galaxies that had a significant deficit of dark matter.

“We expected to find a larger fraction of dark matter,” said Danieli, who co-authored the new study. “We were very surprised by the lack of dark matter.”

As a result of these “lucky findings,” reported by Danieli and van Dokkum in 2018 in Nature and in 2020 in Astrophysical Journal Letters, the paradigm that for The existence of galaxies necessarily requires dark matter.

In the new study, a team led by Jorge Moreno, professor of astronomy at Pomona College, USA, has run numerical simulations of the evolution of a small fragment of the universe – about 60 million light-years in diameter – from the Big Bang to the present.

As a result of the calculations, the team found seven galaxies devoid of dark matter. After several collisions with nearby galaxies that were about 1,000 times as massive, the smaller galaxies were stripped of much of their material, leaving only stars and some residual dark matter in their place.

These results suggest that dark matter-deficient galaxies may be widespread in the universe, especially in the vicinity of massive galaxies, the authors explained.


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