New research has revealed the distribution of dark matter in never-before-seen detail, at a scale of 30,000 light-years. The observed distribution fluctuations provide better constraints on the nature of dark matter. Mysterious dark matter makes up most of the matter in the Universe. Dark matter is invisible and only manifests through its gravitational effects. Dark matter has never been isolated in a laboratory, so researchers must rely on “natural experiments” to study it. One type of natural experiment is gravitational lensing. Sometimes, by chance, two objects at different distances in the Universe will be in the same line of sight when viewed from Earth. When this happens, the spatial curvature caused by the material surrounding the foreground object acts like a lens, bending the path of light coming from the background object and creating an image. through the lens. However, it is difficult to achieve high resolution to detect dark matter clusters less massive than galaxies in natural experiments, so the exact nature of dark matter has not been clearly determined. . A team of Japanese researchers led by Professor Kaiki Taro Inoue of Kindai University used ALMA (Atacama Large Millimeter/Submillimeter Array) to study the gravitational lens system named MG J0414+0534 towards Taurus. In this system, the foreground object forms not one but four images of the background object due to the gravitational pull of a large galaxy on the light. Using curvature effects and new data analysis methods, the team was able to detect fluctuations in the distribution of dark matter along the line of sight with higher resolution than ever before, up to 30,000 light years. The new constraints provided by the observed distribution are consistent with slow-moving or “cold” dark matter particle models. Moving forward, the team plans to further constrain the nature of dark matter through additional observations.
K. T. Inoue et al. “ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Quasar MG J0414+0534” in the Astrophysical Journal, DOI: 10.3847/1538-4357/aceb5f