NextFin news, An international team of astronomers has detected the smallest dark matter clumps ever observed in the early universe, approximately 10 billion light-years from Earth. The discovery was announced on Saturday, October 12, 2025, and marks a significant advancement in understanding the nature of dark matter.
The research team, led by Devon Powell from the Max Planck Institute for Astrophysics in Garching, Germany, used a technique called Very Long Baseline Interferometry (VLBI). This method combines radio telescopes around the globe, including the Very Long Baseline Array (VLBA) in the United States and the European VLBI Network (EVN), to create a virtual telescope the size of the Earth, achieving unprecedented resolution.
The target of their observations was the gravitational lens system JVAS B1938+666. In this system, a massive foreground galaxy bends the light from a more distant radio galaxy behind it, acting like a cosmic lens. By applying newly developed algorithms, the team precisely modeled the lensing effect and reconstructed a sharp image of the background galaxy.
During this analysis, the researchers identified a small but significant anomaly in the lensing image—a subtle 'wobble' indicating the presence of an invisible mass clump associated with the lensing galaxy. This clump has a mass exceeding one million times that of the Sun, making it the least massive structure detected at such a distance and with this method.
The findings were published in two companion papers in the journals Nature and Monthly Notices of the Royal Astronomical Society. Chris Fassnacht, an astronomer at the University of California, Davis, and a study participant, described the detection as an impressive achievement given the object's mass and distance.
This discovery supports the Lambda Cold Dark Matter (Lambda-CDM) cosmological model, which posits that dark matter consists of heavy, slow-moving particles that cluster into structures of various sizes, from large galactic halos to very small clumps. Detecting such a small clump aligns with predictions of this model.
However, the researchers caution that alternative explanations cannot be ruled out. The object might also be an ultracompact dwarf galaxy too faint to be directly observed with current telescopes. While the object's properties better fit a dark matter halo, definitive proof remains pending.
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