Dark matter is thought to make up 85 percent of all matter in the universe but so far we have no direct evidence it exists. There are plenty of good reasons to believe that there is indeed a substance that doesn’t interact with light only gravity, but until its properties are measured we need to keep some healthy skepticism. Now a proposal for studying said properties plans to use gravitational waves, the ripples in space-time.
An international team of cosmologists has run computer simulations to work out what to expect in a specific scenario where dark matter interacts with neutrinos. If collisions between both of these elusive types of particles happen, then smaller dark matter haloes that surround galaxies would evaporate away. These halos, big and small, are the place where galaxies form.
Smaller galaxies are also places where it is more likely for black holes to collide. The simulations show that if the smaller dark matter haloes are gone, then we’d have a lot fewer collisions between black holes in the distant universe. Studying if and how the merger rate changed could provide many insights into dark matter.
“One of the things I’m interested in doing is figuring out new ways of using those observations to learn something about fundamental physics,” Dr Alex Jenkins of University College London, co-author of a new preprint paper presented at the National Astronomical Meeting 2023, told IFLScience. “What we’ve shown is that by looking at the gravitational wave signals that we observe in a particular way, you can infer whether dark matter does interval over particles or not.”
Dr Jenkins noted that the idea to look for the presence or absence of these halos has long been considered a valuable tool. Astronomers have long been using various sources of light, including the cosmic microwave background – the so-called light echo of the Big Bang – to search for such a signal, but the simulations show that the gravitational waves are much better.
“We think our methods will be roughly 100 times more sensitive than the kind of best current observation using light,” Dr Jenkins explained.
So what are we waiting for, shouldn’t we get this prediction tested ASAP? Well, we’re waiting for the next generation of gravitational wave detectors to be built. LIGO, VIRGO, and KAGRA can see events that are far in the cosmos but not far enough. The Einstein Telescope in Europe and the Cosmic Explorer in the US would have the sensitivity to detect this effect, but they have only just been proposed.
“Gravitational waves offer us a unique opportunity to observe the early universe, as they pass unhindered through the universe, and next-generation interferometers will be sensitive enough to detect individual events at huge distances,” Markus Mosbech of the University of Sydney, another co-author, said in a statement.
Another member of the research team, Professor Mairi Sakellariadou of King’s College London, explained that “Third-generation gravitational wave data will offer a novel and independent way to test the current model that describes the evolution of our universe, and shed light on the yet unknown nature of dark matter.”
The study will be published in Physical Review D and is available now on the ArXiv.
Source Link: The True Nature Of Dark Matter Might Be Found With Gravitational Waves
