Scientists Just Discovered How to Track the Speed of Dark Matter
As non-luminous particles floating around in space, dark matter has become one of the most fascinating—and difficult to study—phenomena in astrophysics.
Researchers believe they can finally tell just how fast dark matter travels, however, as a new study published today shows that dark matter and metal-poor stars similar properties of motion. Using a computer simulation called Eris, which replicates the physics of our galaxy and the dark matter in it using supercomputers, the researchers discovered that the velocity of dark matter lined up perfectly with the velocity of stars that contained both heavy metals and lighter elements.
"Using the high-resolution eris simulation, which traces the evolution of both the dark matter and baryons in a realistic Milky Way analog galaxy, we demonstrate that metal-poor stars are indeed effective tracers for the local, virialized dark matter velocity distribution," says the study's abstract.
"The dark matter and these old stars have the same initial conditions: they started in the same place and they have the same properties..." study co-author Lina Necib said. "[S]o at the end of the day, it makes sense that they're both acted on only through gravity."
While we've been able to study dark matter since 2009, this study is significant because it confirms why slowing down dark matter is so important. The researchers' theory is that, if dark matter particles are both slow and light, they may not possess the necessary kinetic energy to move the nuclear particles when they collide.
"But if the dark matter comes in moving faster, it's going to have more kinetic energy," said study co-author Mariangela Lisanti. "That can increase the chance that in that collision, the recoil of the nucleus is going to be greater, so you'd be able to see it."
Though purely theoretical, the researchers hope that working out the speed of dark matter through an independent process might allow them to discover the distribution of speed is not what they expected, thus allowing them to actually see the dark particles in action. This might require "dark matter" to undergo some sort of name change.
NASA has recently suggested that 85-95 percent of the universe is made up of dark energy and dark matter. While searching for dark matter late last year, China accidentally discovered a whole new type of matter altogether. This goes to show how little we actually know about the dark matter particles, which astronomers have suggested is actually comprised of black holes.