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A study reveals that we live in the ruins of an epic galactic collision

Ghost Encounter

A collision with a "ghost of a galaxy" millions of years ago still haunts the Milky Way.

In November, astronomers announced the discovery of Antlia 2, a low density but relatively massive galaxy orbiting the Milky Way.

A team at the Rochester Institute of Technology has proven that a previous galactic collision with Antlia 2 was causing large ripples in the Milky Way's hydrogen disk, which could solve a mystery that has puzzled scientists for more than a year. ten years.

Galactic Collision

Rochester Assistant Professor Sukanya Chakrabarti presented her team's findings, which were submitted to the Commission. The letters of the astrophysical journal and are currently published on the arXiv pre-print server, at a meeting of the American Astronomical Society on Wednesday.

From the data collected by the Gaia satellite of the European Space Agency, they calculated the past trajectory of Antlia 2 and discovered that it was probably colliding with the Milky Way hundreds of millions of years ago, which provoked the ripples that we still see today.

The team also conducted simulations to rule out a previously proposed ripple cause: a galactic collision with the Sagittarius dwarf galaxy.

Dark Matters

Chakrabarti thinks that Antlia 2 could also help scientists solve another mystery: dark matter.

"We do not understand what is the nature of the dark matter particle," she said in a press release, "but if you think you know how much dark matter there is, there's nothing left to do. determine the variation of the density as a function of the radius. "

"If Antlia 2 is the dwarf galaxy we predicted, you know which orbit it should be," she continued. "You know he had to get close to the galactic disk. This imposes strict constraints not only on the mass, but also on its density profile. This means that you can use Antlia 2 as a unique laboratory to learn more about the nature of dark matter. "

READ MORE: New evidence shows that a crash with Antlia 2 gave the Milky Way the ripples of its external drive [Rochester Institute of Technology]

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