1 00:00:00,020 --> 00:00:04,040 [Music] 2 00:00:04,060 --> 00:00:08,090 [Music] 3 00:00:08,110 --> 00:00:12,110 [Music] 4 00:00:12,130 --> 00:00:16,160 Narrator: Dark matter makes up about 27 percent 5 00:00:16,180 --> 00:00:20,170 of the cosmos, but so far no one knows what it is. 6 00:00:20,190 --> 00:00:24,170 Dark matter neither emits nor absorbs light and it 7 00:00:24,190 --> 00:00:28,180 interacts with the rest of the universe primarily through gravity. 8 00:00:28,200 --> 00:00:32,240 In fact, it's thought dark matter traced the initial framework of the 9 00:00:32,260 --> 00:00:36,260 cosmos, attracting normal matter that formed stars and galaxies. 10 00:00:36,280 --> 00:00:40,320 Black holes are astronomical objects famed for their 11 00:00:40,340 --> 00:00:44,330 extreme gravity. Jeremy Schnittman, an astrophysicist at 12 00:00:44,350 --> 00:00:48,370 NASA's Goddard Space Flight Center, wondered if they could serve as a kind of 13 00:00:48,390 --> 00:00:52,440 laboratory for exploring different dark matter models. [Dr. Schnittman]: The leading 14 00:00:52,460 --> 00:00:56,540 particle physics model for dark matter is called weakly 15 00:00:56,560 --> 00:01:00,630 interacting massive particles, or also known as WIMPS. These guys just 16 00:01:00,650 --> 00:01:04,650 fly through the universe without even bumping into anything 17 00:01:04,670 --> 00:01:08,690 or each other. The idea of two WIMPS coming together, 18 00:01:08,710 --> 00:01:12,720 annihilating, and forming gamma rays, is kind of like two bullets hitting 19 00:01:12,740 --> 00:01:16,740 head-on in a crossfire--it's very rare. But when you 20 00:01:16,760 --> 00:01:20,810 go to the area around a supermassive black hole, we expect the 21 00:01:20,830 --> 00:01:24,830 density to be much higher so the probability of annihilation is much higher 22 00:01:24,850 --> 00:01:28,950 and thus detection with a gamma-ray telescope. 23 00:01:28,970 --> 00:01:33,040 Narrator: In Schnittman's computer simulation, a population 24 00:01:33,060 --> 00:01:37,070 of dark matter particles orbits a rapidly spinning black hole. 25 00:01:37,090 --> 00:01:41,170 Close in, at the brink of the black hole's event horizon, the particles 26 00:01:41,190 --> 00:01:45,190 are orbiting at nearly the speed of light. The lightly shaded region 27 00:01:45,210 --> 00:01:49,210 farther out is the ergosphere, a zone where all particles are forced 28 00:01:49,230 --> 00:01:53,280 to move in the same direction as the black hole's spin. 29 00:01:53,300 --> 00:01:57,350 The concentrated dark matter collides and makes gamma rays, 30 00:01:57,370 --> 00:02:01,370 but not all of this light can escape the ergosphere. The gamma rays 31 00:02:01,390 --> 00:02:05,410 most likely to make it out come from the left side, where the black hole spins 32 00:02:05,430 --> 00:02:09,440 toward us. The result is an asymmetric glow. 33 00:02:09,460 --> 00:02:13,490 The highest energy gamma rays come from the center of this region, 34 00:02:13,510 --> 00:02:17,560 corresponding to the black hole's equator. Schnittman's work has 35 00:02:17,580 --> 00:02:21,610 uncovered previously overlooked orbits that can produced extremely energetic 36 00:02:21,630 --> 00:02:25,670 gamma rays, and has shown that the peak energy attainable for this escaping light 37 00:02:25,690 --> 00:02:29,750 is a strong function of the black hole's rotation. 38 00:02:29,770 --> 00:02:33,850 So far, the initial work is focusing on setting upper limits on dark matter 39 00:02:33,870 --> 00:02:37,900 annihilation rates by looking at otherwise quiescent galaxies. But Schnittman's 40 00:02:37,920 --> 00:02:41,950 ultimate ambition is nothing short of an unambiguous detection of dark matter 41 00:02:41,970 --> 00:02:45,990 annihilation around supermassive black holes. [Dr. Schnittman]: To me, 42 00:02:46,010 --> 00:02:50,130 dark matter, black holes, two of the most elusive things in the 43 00:02:50,150 --> 00:02:54,190 universe coming together to help explain each other 44 00:02:54,210 --> 00:02:58,240 is quite poetic. [Music] 45 00:02:58,260 --> 00:03:02,310 [Beeping] 46 00:03:02,330 --> 00:03:06,350 [Beeping] 47 00:03:06,370 --> 00:03:13,240 [Beeping]