Recently discovered ‘ghost galaxy’ had an epic collision that formed the Milky Way

The Milky Way galaxy which serves as home to Earth is likely the result of an epic galactic collision, according to a new study from researchers at the Rochester Institute of Technology.

Science Alert reports that the collision probably took place with a smaller galaxy which is orbiting the Milky Way:

“Antlia 2, the ‘ghost of a galaxy’ orbiting the Milky Way, is a dark horse in more ways than one. Not only is it so faint it was only just discovered last year, it may now be responsible for curious ripples in the hydrogen gas that makes up the Milky Way’s outer disc.

“Antlia 2’s current position is consistent with a collision with the Milky Way hundreds of millions of years ago that could have produced the perturbations we see today.”

Antlia 2 “ghost galaxy” shown in relation to the Milky Way. Photo via NASA

Antlia 2 has been called a “ghost galaxy” by some, and it now appears it was instrumental in the formation of our own galaxy, Rochester Assistant Professor Sukanya Chakrabarti remarked:

We don’t understand what the nature of the dark matter particle is, but if you believe you know how much dark matter there is, then what’s left undetermined is the variation of density with radius.

“If Antlia 2 is the dwarf galaxy we predicted, you know what its orbit had to be. You know it had to come close to the galactic disc. That sets stringent constraints, therefore, on not just on the mass, but also its density profile. That means that ultimately you could use Antlia 2 as a unique laboratory to learn about the nature of dark matter.”

Translation: We could soon learn more about the very origins of the universe as we know it, all thanks to a tiny galaxy that seems to have an affinity for the Milky Way.

Think of the collision between the Milky Way and Antlia 2 as a sort of cosmic duel that left Antlia badly damaged, according to ExtremeTech:

“So, the Milky Way is still largely the same as it was before running into Antlia 2. However, the smaller galaxy was wrecked by the gravity of its larger neighbor. That accounts for the very diffuse current state. The team also used its models to rule out another alleged candidate for the cause of those ripples in the Milky Way: the Sagittarius dwarf galaxy. The model projects no likely collisions between that galaxy and the Milky Way in the past. This work could solve the ripple mystery.”

Some scientists are also predicting another collision, this one between the Milky Way and another galaxy, Andromeda. had this to say about it in February:

“The monster collision between our Milky Way and fellow spiral galaxy Andromeda will occur about 4.5 billion years from now, according to the new research, which is based on observations made by Europe’s Gaia spacecraft. Some prominent previous estimates had predicted the crash would happen significantly sooner, in about 3.9 billion years.”

In other words, we don’t have to worry about that event for a very long time.

Featured Image Via JPL/NASA

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