A potential solution to the decades-long “missing matter” problem has been uncovered as astronomers’ recent analysis of X-ray data identifies a filament of hot gas, 10 times the size of the Milky Way, filling the space between four galaxy clusters.
While the discovery does not completely answer the question of where all of the currently unaccounted for matter resides, the filament does appear to represent a significant chunk of it. Astronomers sourced the data used in the new research from the European Space Agency’s XMM-Newton and JAXA’s Suzaku X-ray space telescopes.
Missing Matter
Current models of the universe have a major shortcoming: they can’t fully account for all the matter that should exist. While dark matter and dark energy—detectable only by their effects—compose most of the cosmos, visible matter accounts for just about 5%. Yet even among that 5%, nearly half of the expected matter remains missing.
One possible explanation is the existence of long, tenuous strings of gas called “filaments.” However, detecting these structures is notoriously difficult, as they are extremely faint and often obscured by brighter cosmic phenomena like galaxies and black holes. The breakthrough in the new research lies in the team’s successful identification and characterization of a hot gas filament connecting four galaxy clusters.
“For the first time, our results closely match what we see in our leading model of the cosmos – something that’s not happened before,” says lead researcher Konstantinos Migkas of Leiden Observatory in the Netherlands. “It seems that the simulations were right all along.”
Identifying the Missing Matter
The four galaxy clusters and the filament linking them are part of the Shapley Supercluster, one of the largest known structures in the universe, containing around 8,000 galaxies. Two clusters sit on each side of the filament, which stretches 23 million light-years diagonally away from Earth.
XMM-Newton and Suzaku’s X-ray data were crucial to mapping the filament’s properties, supported by optical data from multiple sources. Each telescope contributed a unique perspective: Suzaku scanned a broad area of space, while XMM-Newton focused on identifying supermassive black holes within the filament and removing their interference from the data.
“Thanks to XMM-Newton we could identify and remove these cosmic contaminants, so we knew we were looking at the gas in the filament and nothing else,” adds co-author Florian Pacaud of the University of Bonn, Germany. “Our approach was really successful, and reveals that the filament is exactly as we’d expect from our best large-scale simulations of the Universe.”
Hellbound and Down 