I finally looked this up because it makes no sense. Two sensors that see a ripple in space at slightly different times gives you a broad arc at best and a full 2D plane at worst. So, when they say, "LIGO detected a wave and it's that one black hole merger right there, 100% definitely for sure," and that sounds like bullshit, it's because it is. One detector cannot determine directionality. They use triangulation from the 3 different detectors, LIGO, Virgo, and KAGRA. Even then it's more guesswork than they say.
That's important here because Dark Matter is even more subtle and hard to pinpoint AND you can't compare it to telescope data to verify your theory on directionality.