Andromeda to gobble Milky Way in five billion years

Andromeda to gobble Milky Way in five billion years

In five billion years, the Andromeda galaxy will cannibalize the Milky Way due to a recently discovered process where larger galaxies gain mass by eating their smaller neighbors.

According to a recent report from the Royal Astronomical Society, the Andromeda galaxy will cannibalize the Milky Way in approximately five billion years.

Larger growing galaxies, such as Andromeda, frequently consume smaller galaxies instead of producing additional stars from existing gas. The Milky Way isn’t entirely innocent of this practice, either- it’s expected to consume the dwarf galaxies Small and Large Magellanic Clouds in about four billion years before turning into Andromeda’s main course.

Dr. Aaron Robotham of the University of Western Australia’s International Centre for Radio Astronomy Research (ICRAR) and his team studied 22,000 galaxies over multiple years. They discovered that the heaviest galaxies grow by ceasing to produce additional stars and, instead, gobbling up their closest neighbors. This is because larger galaxies are much less productive at star formation and so rely on gaining mass by swallowing their smaller neighbors.

Since Andromeda is a much larger galaxy than the Milky Way, it’s expected to swallow us instead of the other way around. The Milky Way is thought to have cannibalized several other galaxies; some remains of the previously eaten galaxies can still be seen today.

Star formation gradually decreases due to feedback mechanisms in a galaxy’s central star cluster, Robotham explained. “The topic is much debated, but a popular mechanism is where the active galactic nucleus basically cooks the gas and prevents it from cooling down to form stars.”

However, this process does have an end point: eventually, only a few super-massive galaxies would exist after billions and billions of years due to extensive cannibalization of smaller systems. This process, Dr. Robotham cautioned, could take “many times the age of the universe so far.” As the universe is roughly 13.4 billion years old, he’s warning people not to hold their breath for it.

The results were discovered as part of the extensive Galaxy and Mass Assembly (GAMA) project, an effort that has been active over the past seven years.

 

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