Dark Matter Winners And Losers In The Aftermath Of LIGO
“Winner: Cold dark matter. Particularly from the neutron star mergers 130 million light years away, there ought to be a delay in the arrival time of the gravitational wave signal due to intervening matter on the order of a few hundred years. The fact that the arrival of both light waves and gravitational waves were delayed by the same amount provides further evidence for dark matter, especially considering that a quadruply-lensed supernova had already been observed in light waves, demonstrating that dark matter delays the arrival time of light signals. If there were no dark matter, this behavior should be vastly different; our gravitational wave observatories have provided further, independent evidence that dark matter is real.”
LIGO didn’t just detect the gravitational waves from merging black holes, it also gave us a whole slew of information about these ripples and the Universe they traveled through. Alternatives to General Relativity became highly constrained, with many variants of modified gravity getting ruled out. On the other hand, Einstein’s theory emerged stronger than ever. Models which did away with dark matter suffered tremendous setbacks, while standard cold dark matter scored a major victory. Variable speed-of-light theories took a hit, and may be well on their way out. And finally, when you fold in the other results, WIMP dark matter, particularly from supersymmetry, is looking worse and worse as time goes on and new results continue to pour in. What is the dark matter, then? Perhaps, in a stunning turn of events, it may have something to do with the neutrino after all.