Astronomers in Pasadena, California have recently uncovered a groundbreaking revelation within the Perseus galaxy cluster, situated 240 million light-years away from Earth. This discovery marks the first time that a dark matter bridge has been identified, connecting two galaxies that are currently on a collision course.
The study, which was published on April 16 in Nature Astronomy, focuses on a newly detected subcluster positioned 1.4 million light-years to the west of NGC 1275, the central galaxy of the Perseus cluster. This subcluster is linked to the core of Perseus by a faint bridge of material primarily composed of dark matter. James Jee, a member of the research team, expressed that this newfound dark matter bridge serves as the missing puzzle piece that provides clarity to the peculiar shapes and swirling gas within the Perseus cluster, all of which can now be understood in the context of a major merger.
To make this groundbreaking revelation, Jee and his team utilized the Subaru Telescope and its Hyper Suprime-Cam to capture the deepest images ever taken of the Perseus cluster. The key to this discovery lies in gravitational lensing, a phenomenon initially predicted by Albert Einstein, wherein light from distant objects bends due to the gravitational field of massive objects like galaxy clusters.
Through gravitational lensing, the team revealed a massive dark matter clump weighing approximately 200 trillion solar masses, connected to the Perseus core by the faint dark matter bridge. Additionally, the researchers found evidence indicating that this dark matter clump had collided with the Perseus cluster roughly 5 billion years ago, its remnants continuing to shape the cluster’s present structure.
Galaxy clusters, being some of the most massive structures in the universe, grow primarily through intense mergers. For years, astronomers had theorized that the Perseus cluster expanded through such mergers, yet direct evidence had remained elusive until the discovery of the dark matter bridge.
The discovery of this dark matter bridge not only deepens our understanding of the Perseus cluster but also presents new opportunities for studying dark matter, an enigmatic and elusive element of the universe. Jee emphasized the significance of this revelation, emphasizing the integration of deep imaging data from the Subaru Telescope with advanced gravitational lensing techniques that he and his team had developed, showcasing the power of lensing in revealing the hidden dynamics of the universe’s largest structures.