No, not because it was too young to drink! Scientists at the Max Planck Institute for Extraterrestrial Physics were looking at some X-ray objects, and discovered something really weird: a very bright X-ray source moving out of a galaxy at nearly 3,000 kilometers/second! This thing is a goner. If our Sun were moving at even one quarter of that speed, it would get thrown out of our galaxy.
Now, here’s the kicker: this isn’t just any old object getting tossed out of a galaxy, it is a huge black hole! How huge? About 300,000,000 times the mass of our Sun. You read that number right: 300,000,000. So there’s no way this is anything other than a black hole. We’ve only ever found objects this massive at the center of galaxies, where they presumably help hold it together. So how is it that this one is getting kicked out?
Well, the only things that ever give off enough energy to move something that massive that quickly are either giant mergers or giant explosions. But this would have had to be the most powerful supernova in history to cause a nearby black hole that massive to move that quickly. The only explanation that Stephanie Komossa’s team has come up with is that this happened from a huge merger of two humongous black holes. Simulations show that it might have looked something like this:
Up until now, this has only been predicted theoretically, and never observed. The only way that a merger can cause a kick like this is by emitting gravitational waves; this would be another piece of indirect evidence for gravitational radiation, and this is also the exact type of merger that LISA is being designed to look for.
This means a number of cool things, including:
- There are some galaxies that lose their supermassive black holes in the center. Could the Milky Way, with its puny 3,000,000 solar mass black hole, have had this happen in the past?
- Galaxies and their black holes might have formed together, but that’s no guarantee they’ll end up together.
- If the theories are correct, we will be able to detect the gravitational waves coming from these mergers directly in the relatively near (~15 years) future.
So this is big news! I wonder what happens to these ejected black holes? Do they just travel through intergalactic space, eating up whatever’s in their way like giant death stars?
Or do they find their way into other galaxies and merge with them, creating super-duper-massive black holes? It makes me so happy that we can ask these questions, and that we’re starting to understand how one more thing in the Universe works. You can read the full press release here. Hooray for science!