Large Galaxies Grow by Feeding on Smaller Neighbours

Large galaxies feed on stars of smaller galaxies, a new study has found.

According to researchers at the University of Western Australia, small galaxies are efficient in making new stars from gas. The massive galaxies, however, start snacking on these dwarf galaxies instead of making new ones.

"All galaxies start off small and grow by collecting gas and quite efficiently turning it into stars," Dr Aaron Robotham based at The University of Western Australia said in a news release. "Then every now and then they get completely cannibalised by some much larger galaxy."

The study is published in the journal Monthly Notices of the Royal Astronomical Society.

For the study, the researchers looked at data available on more than 22,000 galaxies. They found that monster galaxies resort to cannibalism to grow. Data for the current study came from Anglo-Australian Telescope in New South Wales as part of the Galaxy And Mass Assembly (GAMA) survey.

The researchers say that our own galaxy - the Milky Way - has eaten several small galaxies in the past. "We're also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds, in about four billion years," Dr Robotham said in a news release.

The Milky Way, however, will get its punishment for eating dwarf galaxies, researchers said. In about five billion years, our galaxy will merge with the nearby Andromeda Galaxy. "Technically, Andromeda will eat us because it's the more massive one," Robotham said.

Galactic canaballism isn't a new idea. Astronomers have already known that massive galaxies grow by feeding on their smaller counterparts. A study from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) had recently said that large galaxies have lost their appetite and are now not eating as many stars as they once used to.