Using computer simulations, an international team of cosmologists have discovered that observations of gravitational waves from merging black holes may unveil the true nature of dark matter. Their findings are presented at the 2023 National Astronomy Meeting in Cardiff this week by co-author Dr Alex Jenkins of University College London.
The team used computer simulations to study the production of gravitational wave signals in simulated universes with different kinds of dark matter. Their findings show that counting the number of black-hole merging events detected by the next generation of observatories could tell us whether or not dark matter interacts with other particles, giving us new insights into what it is made of.
Cosmologists generally regard dark matter as one of the biggest missing pieces in our understanding of the cosmos. Despite strong evidence that dark matter makes up 85% of all the matter in the Universe, there is currently no consensus on its underlying nature. This includes questions such as whether dark matter particles can collide with other particles such as atoms or neutrinos, or whether they pass straight through them unaffected.
A way to test this is by looking at how galaxies form in dense clouds of dark matter called haloes. If dark matter collides with neutrinos, the dark matter structure becomes dispersed, resulting in fewer galaxies being formed. The problem with this method is that any galaxies that go missing are very small and very distant from us, so it’s hard to see whether they are there or not, even with the best telescopes available.
Rather than targeting the missing galaxies directly, the authors of this study propose using gravitational waves as an indirect measure of their abundance. Their simulations show that in models where dark matter does collide with other particles, there are significantly fewer black-hole mergers in the distant universe. While this effect is too small to be seen by current gravitational wave experiments, it will be a prime target for the next generation of observatories that are currently being planned.
The authors hope their methods will help stimulate new ideas for using gravitational wave data to explore the large-scale structure of the Universe, and shine a 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 it is especially important to continue identifying new ways to explore models of dark matter, combining both existing and new probes to test model predictions to the fullest. Gravitational wave astronomy offers a pathway to better understand not just dark matter, but the formation and evolution of galaxies more generally.”
Markus Mosbech of the University of Sydney, another co-author, adds, “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.”
Another member of the research team, Professor Mairi Sakellariadou of King’s College London, said, “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 to the yet unknown nature of dark matter.”
University College London
Ms Gurjeet Kahlon
Royal Astronomical Society
Mob: +44 (0)7802 877 700
Ms Megan Eaves
Royal Astronomical Society
Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
Notes for editors
The NAM 2023 conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and Cardiff University.
About the Royal Astronomical Society
The Royal Astronomical Society (RAS, https://ras.ac.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
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About the Science and Technology Facilities Council
The Science and Technology Facilities Council (STFC) is part of UK Research and Innovation – the UK body which works in partnership with universities, research organisations, businesses, charities, and government to create the best possible environment for research and innovation to flourish. STFC funds and supports research in particle and nuclear physics, astronomy, gravitational research and astrophysics, and space science and also operates a network of five national laboratories, including the Rutherford Appleton Laboratory and the Daresbury Laboratory, as well as supporting UK research at a number of international research facilities including CERN, FERMILAB, the ESO telescopes in Chile and many more.
STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory and the Square Kilometre Array Organisation.
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About Cardiff University
Cardiff University is recognised in independent government assessments as one of Britain’s leading teaching and research universities and is a member of the Russell Group - the UK’s most research intensive universities. The 2021 Research Excellence Framework found 90% of the University’s research to be world-leading or internationally excellent. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise encompasses: the College of Arts, Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences and Engineering. Its University institutes bring together academics from a range of disciplines to tackle some of the challenges facing society, the economy, and the environment. More at www.cardiff.ac.uk