Gravitational waves could illuminate dark matter

The future Laser Interferometer Spatial Antenna (LISA) will be a huge instrument that will allow astronomers to study phenomena such as collision of black holes and gravitational waves moving in space-time. Researchers at the University of Zurich have now discovered that LISA can also illuminate this particle of elusive dark matter.

The Space Interferometer with Laser Interferometer (LISA) will allow astrophysicists to observe the gravitational waves emitted by black holes when they collide or capture other black holes. LISA will consist of three spacecraft orbiting the sun in a constant triangle formation. The passage of gravitational waves will slightly deform the sides of the triangle, and these minimal distortions can be detected by laser beams connecting the spacecraft. LISA could therefore add a new meaning to the perception of the universe by scientists and allow them to study invisible phenomena in different light spectrums.

Scientists from the Center for Theoretical Astrophysics and Cosmology at the University of Zurich, as well as colleagues from Greece and Canada, have discovered that LISA would not only be able to measure these previously un-studied waves, but could also help reveal secrets about dark matter. .

Dark matter particles are thought to account for about 85% of the matter in the universe. However, they are still only hypothetical – the name refers to their elusive. But calculations show that many galaxies would be torn instead of rotated if they were not held together by a large amount of dark matter.

This is especially true for dwarf galaxies. Although these galaxies are small and weak, they are also the most abundant in the universe. What makes them particularly interesting for astrophysicists is that their structures are dominated by dark matter, making them natural laboratories for studying this elusive form of matter.

Black holes and dark matter are connected

In a new study reported in Astrophysical Journal Letters, Ph.D. UZH Student Tomas Ramfal has performed high-resolution computer simulations of the birth of dwarf galaxies, yielding surprising results. By calculating the interaction of dark matter, stars and central black holes of these galaxies, the team of Zurich scientists discovered a close link between the melting rates of these black holes and the amount of material black in the center of dwarf galaxies. The measurement of the gravitational waves emitted by the fusion of black holes can therefore provide indications on the properties of the hypothetical dark matter particle.

The new link found between black holes and dark matter can now be described mathematically and accurately for the first time. Lucio Mayer, the leader of the group, said, "Dark matter is the quality that distinguishes dwarf galaxies, so we had long suspected that this should also have a clear effect on cosmological properties."

The connection is timely, as preparations for the final LISA design are underway. Preliminary results of the researchers' simulations sparked enthusiasm at the LISA consortium meetings. The physics community sees the new use of gravitational wave observations as a promising new prospect for one of Europe's largest future space missions, which is expected to be launched in around 15 years and could link cosmology and physics with particles – the incredibly tall and the small.

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More information:
Tomas Tamfal et al, LISA black hole binary formation in the fusion of dwarf galaxies: the dark matter footprint, The astrophysical journal (2018). DOI: 10.3847 / 2041-8213 / aada4b