As I've written about many, many times in the past, we think that all big galaxies have supermassive black holes in their centers. These black holes can have up to billions of times the mass of the Sun, and almost certainly formed at the same time as the galaxies themselves.
But there are also dwarf galaxies out there, ones that are much smaller and much lower mass than, say, the Milky Way. In fact, our galaxy is orbited by dozens of dwarf galaxies, and dwarfs are almost certainly the most common kind of galaxy in the Universe (for a given kind of object, Nature tends to make lots of little things and fewer big things; break a rock with a hammer to see this effect in action).
So do dwarf galaxies have supermassive black holes? And if so, what can we learn from them?
Artwork depicting a black hole with an accretion disk, and magnetic fields swirling above it. Credit: NASA/JPL-Caltech
Very few dwarf galaxies are known to host these monsters; a likely one was found in 1989 and another in 2004. In 2011, astronomers discovered a supermassive black hole (with a mass of about one million suns) in the ...