Observing gravitational waves from merging black holes could provide new insights into the nature of dark matter, researchers have revealed, according to findings presented at the National Astronomical Meeting in 2023. The international team used computer simulations to investigate the generation of signals from gravitational waves in simulated universes with different types of dark matter. They suggest that counting black hole merger events detected by next-generation observatories could reveal whether dark matter interacts with other particles.
Gravitational waves from merging black holes could reveal the nature of dark matter, according to computer simulations presented at the 2023 National Astronomical Meeting.
Using computer simulations, an international team of cosmologists found that observations of gravitational waves from merging black holes may reveal the true nature of dark matter. Their findings were presented at the 2023 National Astronomical Meeting in Cardiff by co-author Dr Alex Jenkins of University College London.
The team used computer simulations to investigate the production of gravitational wave signals in simulated universes with different types of dark matter. Their findings show that counting the number of black hole merger events detected by the next generation of observatories can tell us whether or not dark matter interacts with other particles, giving us new insights into what it’s made of.
Cosmologists generally consider dark matter to be one of the biggest missing pieces in our understanding of the cosmos. Despite strong evidence that dark matter makes up 85% of all matter in the universe, there is currently no consensus on its fundamental nature. This includes questions such as whether dark matter particles can collide with other particles such as atoms or neutrinos, or whether they pass right through them unaffected.
One way to check this is by looking at how galaxies form in dense clouds of dark matter called haloes. If dark matter collides with neutrinos, the structure of dark matter is dispersed, resulting in the formation of fewer galaxies. The problem with this method is that all the extinct galaxies are very small and very far away from us, so it is difficult to see whether they are there or not, even with the best telescopes available.
Instead of targeting the missing galaxies directly, the authors of this study suggest using gravitational waves as an indirect measure of their abundance. Their simulations show that in models where dark matter collides with other particles, there are significantly fewer black hole mergers in the distant universe. Although this effect is too small to be seen by current gravitational wave experiments, it will be a major target for the next generation of observatories currently being planned.
The authors hope their methods will help stimulate new ideas for using gravitational wave data to study the large-scale structure of the universe and shed new light on the mysterious nature of dark matter.
Co-author Dr Sownak Bose of Durham University said: “Dark matter remains one of the enduring mysteries in our understanding of the universe. This means that it is especially important that we continue to identify new ways to probe dark matter models, combining both existing and new probes to test the model’s predictions to the fullest extent. Gravitational wave astronomy offers a path to better understanding not only dark matter, but also the formation and evolution of galaxies more generally.
Markus Mosbech from University of Sydneyanother co-author, adds: “Gravitational waves offer us a unique opportunity to observe the early universe as they travel unhindered through the universe, and next-generation interferometers will be sensitive enough to detect individual events at vast distances.”
Another member of the research team, Professor Mairi Sakellariadou from King’s College London, said: “Third-generation gravitational wave data will offer a new and independent way of testing the current model that describes the evolution of our Universe, and will shed light on everything still unknown nature of dark matter.
The NAM 2023 conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and Cardiff University.