Black holes pose several interesting questions for researchers due to their apparent ability to grab hold of information, light, and matter, and never let any of it go. The truth is though that the information can escape, but you have to be clever with how to find it. Researchers at the European Space Agency and Harvard-Smithsonian Center for Astrophysics have recently managed to read some of the secrets of the supermassive black hole at the center of galaxy NGC 1365.
Due to the laws of gravity, black holes are actually somewhat easy to describe as all you need is its mass and spin, though of course how it interacts with the rest of the Universe can be very complex. The mass of these particular black hole has already been found to be several million solar masses, but its spin was a little fuzzy, which is why the researchers aimed the XMM-Newton and NuStar satellite telescopes at it. These observatories are both able to collect X-rays, such as those emitted by matter shortly before it falls into the black hole. By determining the distance of that matter from the black hole, the researchers were able to calculate its spin, and it is fast at relativistic speeds.
As a result of knowing the black hole's rate of spin, the researchers can determine how it must have grown to its current size. If the black hole and been feeding on mass that randomly entered it, that randomness would have slowed it down, but because it is rotating so quickly, it must have been fed by a relatively uniform stream of mass. As supermassive black holes have a great impact on the galaxies they are within, this information also tells us about the galaxy and its history.