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New galactic test clarifies existence of dark matter

"We have now simulated, for the first time, the RAR of dwarf galaxies on the assumption that dark matter exists," said astronomer Cristiano Porciani.

By Brooks Hays
New galactic test clarifies existence of dark matter
New simulations have helped scientists determine how satellite dwarf galaxies would behave with or without the influence of dark matter. Photo by E. Garaldi/C. Porciani/E. Romano-Díaz/University of Bonn for the ZOMG Kollaboration

June 25 (UPI) -- New computer models designed to simulate the distribution of dwarf galaxies surrounding the Milky Way have clarified the existence of dark matter.

The models helped researchers simulate "radial acceleration relation," or RAR, the relationship between the movement of satellite galaxies caused the attraction between galactic matter.

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RAR considers the observed circular acceleration of a galaxy and the acceleration explained by the galaxy's distribution of ordinary matter.

The new models account for acceleration caused by dark matter, as well.

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"We have now simulated, for the first time, the RAR of dwarf galaxies on the assumption that dark matter exists," Cristiano Porciani, a researcher with the Argelander Institute for Astronomy at the University of Bonn, said in a news release. "It turned out that they behave as scaled-down versions of larger galaxies."

The simulations also allowed scientists to determine how satellite galaxies would most likely behave in the absence of dark matter. Models showed, without dark matter, a satellite galaxy's RAR would be more directly influenced by its distance from the parent galaxy.

The European Space Agency's Gaia spacecraft is currently collecting precise details about size, trajectory and velocity of millions of stars, including stars inside the many dwarf galaxies circling the Milky Way.

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Scientists hope the Gaia data can be used to test the predictions of the newest RAR models with the galactic observations. However, astronomers may have to wait for sufficient amounts of data.

"Individual measurements are not enough to test the small differences we have found in our simulations," said Bonn doctoral student Enrico Garaldi. "But repeatedly taking a close look at the same stars improves the measurements every time. Sooner or later it should be possible to determine whether the dwarf galaxies behave like in a universe with dark matter -- or not."

The existence of dark matter is implied by its gravitational influence, but it has yet to be directly detected. Most astronomers agree that dark matter exists. Dark matter's presence solves a variety of astrophysical problems.

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However, some scientists have argued alternative theories of gravity could plug some of the same theoretical gaps, making new test for the existence dark matter necessary.

Astronomers detailed the newest proposed test in the journal Physical Review Letters.

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