So headlines like these make me happy. Even if you don’t share my interest in 2nd heaven ‘waters’ or fluid dark matter (whether it’s concordism 
or just a cool metaphor), it’s fascinating science, right? 
So awesome we have people who study this in the time in which we live. I am so glad I started learning about cosmology. I really doubt the average person has any idea how cool space actually is. I suppose for our culture it has been like looking at the ocean - it looks very uniform on the surface, but when you dive in, there’s a world more fascinating than the one on land.
As the Large Magellanic Cloud, or LMC, sails through this region, it should leave a wake behind. The stars seen trailing the LMC in the new star map are thought to be the outline of this dark matter wake, with the stars “floating” on it like flotsam on an invisible ocean.
“We think this wake is made up of dark matter, and it drags stars along with it, which is how we can detect it,” said Nicolás Garavito-Camargo , a UArizona doctoral student who is part of a research group led by Gurtina Besla , an associate professor of astronomy at UArizona’s Steward Observatory. Both are co-authors on the Nature paper.
Various theories exist about the nature of dark matter, and each predicts different properties for the halo of the Milky Way. For this study, Besla, Garavito-Camargo and colleagues used a dark matter theory known as cold dark matter, which is currently favored by astrophysicists. The location and appearance of the LMC’s wake may be different if another model for dark matter were used, according to Besla and Garavito-Camargo.
“You can imagine that the wake behind a boat will be different if the boat is sailing through water or through honey,” Conroy said. “In this case, the properties of the wake are determined by which dark matter theory we apply.”
Besla’s team is running similar tests with different dark matter theories, to see which one best matches the wake observed in the stars.