Using Gravitational Waves to Hunt for Dark Matter

A global team of cosmologists has discovered through computer simulations that observing gravitational waves from merging black holes can reveal the real nature of dark matter. Dr. Alex Jenkins of University College London will co-author their discovery today at the 2023 National Astronomy Meeting.

The team studied the production of gravitational wave signals in simulated universes with various types of dark matter through computer simulations. Their findings show that counting the number of black hole merger events found by the next generation of observatories can tell us whether or not dark matter interacts with other particles. This gives us new insights into what it is made of.

The understanding of cosmologists

Cosmologists generally believe that our understanding of the cosmos lacks dark matter. Despite solid evidence that it accounts for 85% of all matter in the universe, there is no current consensus on the underlying nature of dark matter. This covers whether dark matter particles can collide with others, such as atoms or neutrinos, or can pass directly through them unaffected.

To verify this, you can look at how galaxies form into haloes, dense clouds of dark matter. The structure of the dark matter disperses when it collides with the neutrinos, resulting in fewer galaxies forming. The problem with this method is that all the galaxies that disappear are tiny and very far away from us. Even with the best telescopes available, it is difficult to determine whether they are there.

Exploring the Structure of the Universe Through Gravitational Waves: Future Perspectives

The authors of this study suggest using gravitational waves to indirectly measure the abundance of vanishing galaxies rather than seeing them directly. Their simulation shows far fewer black hole mergers in the distant universe in models where dark matter collides with other particles. Although this effect is too small to be observed by the gravitational-wave experiments currently being performed, it will be an important target for the next generation of observatories that are being planned.

The authors hope their methods will stimulate new ideas for using gravitational-wave data to explore the universe’s large-scale structure and shed new light on the mysterious nature of dark matter.

Dr. Sownak Bose of Durham University, a co-author, said: Our understanding of the universe still faces many mysteries, including dark matter. This indicates that it is crucial to continue discovering new ways to study dark matter models, combining new and existing probes to test model predictions as much as possible. The study of gravitational wave astronomy allows for a better understanding of dark matter and the formation and evolution of galaxies in general.

Co-authors’ Statements on Gravitational Waves and the Evolution of the Universe

The other co-author, Markus Mosbech of the University of Sydney, added: As they pass unimpeded through the universe, gravitational waves offer us a unique opportunity to observe the early universe, and next-generation interferometers will be sensitive enough to detect individual events over enormous distances.

Professor Mairi Sakellariadou of King’s College London, another member of the research team, said: The third generation gravitational wave data will provide a new and independent way to test the current model describing the evolution of our universe and shed light on the still unknown nature of dark matter.

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