Astronomers say they have made the most precise measurement of dark matter yet – although they are still yet to, you know, actually find it.
In extensive research known as the Kilo-Degree Survey (KiDS), scientists are in the process of analyzing 20 million galaxies to see how dark matter has influenced the evolution of the universe. They have studied about 2 million so far, completing 7% of the survey, but already the results are looking intriguing.
Many galaxies are known to live in groups, such as our own Milky Way, which resides in the Local Group. These collections of galaxies are thought to be largely dictated by dark matter, which is estimated to be 30 times more abundant than visible matter. This survey has shown that the brightest galaxy in the group will almost always sit in the middle of the dark matter clump, for reasons that aren’t entirely understood.
Massimo Viola from Leiden Observatory in the Netherlands, lead author on one of the several papers to come out of the survey so far, told IFLScience that the research also revealed information on star formation in galaxies. “We clearly show that the dominant mechanism to actually suppress the formation of stars in the central galaxies is the active galactic nuclei [AGN],” he said, referring to the compact region at the center of galaxies where a supermassive black hole likely resides.
This survey, which will take a few more years to complete, is being performed using the European Southern Observatory's (ESO) VLT Survey Telescope (VST) at the Paranal Observatory in Chile.
It is gathering data by measuring weak gravitational lensing – the effects of gravity on the light of galaxies – caused by dark matter. Two other similar surveys are also taking place at the moment, the Dark Energy Survey and Hyper Suprime-Cam, and together all three will give us our best understanding yet of one of the universe’s biggest mysteries.
“The final goal is to test the cosmological model by proving the dark matter distribution at different epochs in the universe,” Viola explained. “It’s a very exciting moment in astrophysics.”