Massive galaxies in the universe have stopped making new stars and are instead gulping down nearby galaxies, according to new research.
According to Australian researchers, our own Milky Way is at a tipping point and expected to now grow mainly by eating smaller galaxies, rather than by collecting gas.
"The Milky Way has not merged with another large galaxy for a long time, but you can still see remnants of all the old galaxies we have cannibalised," explained Aaron Robotham from the International Centre for Radio Astronomy Research (ICRAR) at University of Western Australia.
"Our Milky Way is going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds, in about four billion years," he said.
Australian astronomers looked at more than 22,000 galaxies and found that while smaller galaxies were very efficient at creating stars from gas, the most massive galaxies were much less efficient at star formation, producing hardly any new stars themselves, and instead grew by eating other galaxies.
"All galaxies start off small and grow by collecting gas and quite efficiently turning it into stars. Then every now and then they get completely cannibalised by some much larger galaxy," Robotham added.
The study was published in the journal Monthly Notices of the Royal Astronomical Society.