[Music] [Music] [Music] Narrator: Dark matter makes up about 27 percent of the cosmos, but so far no one knows what it is. Dark matter neither emits nor absorbs light and it interacts with the rest of the universe primarily through gravity. In fact, it's thought dark matter traced the initial framework of the cosmos, attracting normal matter that formed stars and galaxies. Black holes are astronomical objects famed for their extreme gravity. Jeremy Schnittman, an astrophysicist at NASA's Goddard Space Flight Center, wondered if they could serve as a kind of laboratory for exploring different dark matter models. [Dr. Schnittman]: The leading particle physics model for dark matter is called weakly interacting massive particles, or also known as WIMPS. These guys just fly through the universe without even bumping into anything or each other. The idea of two WIMPS coming together, annihilating, and forming gamma rays, is kind of like two bullets hitting head-on in a crossfire--it's very rare. But when you go to the area around a supermassive black hole, we expect the density to be much higher so the probability of annihilation is much higher and thus detection with a gamma-ray telescope. Narrator: In Schnittman's computer simulation, a population of dark matter particles orbits a rapidly spinning black hole. Close in, at the brink of the black hole's event horizon, the particles are orbiting at nearly the speed of light. The lightly shaded region farther out is the ergosphere, a zone where all particles are forced to move in the same direction as the black hole's spin. The concentrated dark matter collides and makes gamma rays, but not all of this light can escape the ergosphere. The gamma rays most likely to make it out come from the left side, where the black hole spins toward us. The result is an asymmetric glow. The highest energy gamma rays come from the center of this region, corresponding to the black hole's equator. Schnittman's work has uncovered previously overlooked orbits that can produced extremely energetic gamma rays, and has shown that the peak energy attainable for this escaping light is a strong function of the black hole's rotation. So far, the initial work is focusing on setting upper limits on dark matter annihilation rates by looking at otherwise quiescent galaxies. But Schnittman's ultimate ambition is nothing short of an unambiguous detection of dark matter annihilation around supermassive black holes. [Dr. Schnittman]: To me, dark matter, black holes, two of the most elusive things in the universe coming together to help explain each other is quite poetic. [Music] [Beeping] [Beeping] [Beeping]