Researchers at the University of Amsterdam have created a new theoretical model to detect dark matter around black holes through gravitational waves. The approach focuses on extreme mass-ratio inspirals and relies on Einstein's general relativity for precise predictions. This could provide insights into dark matter's distribution as future observatories like LISA come online.
A team of physicists from the University of Amsterdam has introduced an advanced method to uncover hidden dark matter using gravitational waves emitted by black holes. The researchers, Rodrigo Vicente, Theophanes K. Karydas, and Gianfranco Bertone, work at the UvA Institute of Physics and the GRAPPA center for gravitation and astroparticle physics. Their study, published in Physical Review Letters in 2025, presents a fully relativistic framework to analyze how dark matter influences these waves.
The model targets extreme mass-ratio inspirals (EMRIs), where a small, dense object, such as a stellar-mass black hole, orbits a much larger supermassive black hole at a galaxy's center. Over time, the smaller object spirals inward, producing gravitational waves that can be observed for extended periods—potentially months or years, encompassing hundreds of thousands to millions of orbits.
Previous studies relied on simplified approximations, often based on Newtonian physics, which overlooked key relativistic effects. The new framework corrects this by fully incorporating Einstein's theory of general relativity. It describes how surrounding matter, including dense dark matter concentrations known as spikes or mounds, alters the orbits and reshapes the emitted waves.
Future missions, like the European Space Agency's Laser Interferometer Space Antenna (LISA), set for launch in 2035, will detect these signals. The researchers show that dark matter structures would leave distinct signatures, or cosmic fingerprints, in the data. This step advances the goal of mapping dark matter across the universe and understanding its properties, as dark matter is thought to comprise most of the universe's matter.
The work emphasizes the need for precise modeling before LISA's observations begin, ensuring accurate interpretation of the signals.