July 19, 2024
If a smaller galaxy and a much larger companion merge, it can spell the end of the smaller galaxy. Indeed, the European Space Agency’s Gaia survey has discovered the bones and corpses of cannibalized galaxies littered throughout the Milky Way.

How are galaxies destroyed?

Eventually, all galaxies, including our own Milky Way, will meet their end.

But how do galaxies die? If you’re in the mood to destroy an entire galaxy, you have several options, depending on your desired level of destructiveness.

Option 1: Wake up the monster black hole 

At the heart of almost every galaxy sits a supermassive black hole. In the case of the Milky Way, we have Sagittarius A*, a beast weighing more than 4.5 million suns. Usually, these giant black holes are quiet and dormant, just sipping on whatever bits of gas or stars that wander too close. But occasionally, they feast on a much larger meal. When they do, that gas swirls around them and compresses, reaching temperatures well over a billion degrees.

Those ridiculously high temperatures cause the gas to give off an enormous amount of radiation that then goes out to flood the entire galaxy, heating up any reserves of gas and preventing the formation of new stars. While things usually calm down after that, in the worst cases, the radiation from the vicinity of the black hole can outright eject massive amounts of gas from the galaxy altogether.

This doesn’t quite destroy a galaxy, but it does effectively kill it by preventing new stars from forming for a very long time and, in some cases, forever.