Thursday, February 22, 2024

Cosmic Dark Matter Web Detected in Coma Cluster


Figure 1: Dark matter in the Coma Cluster region. The distribution of dark matter calculated based on this research (dark green cloud) is overlayed on an image of the Coma Cluster and more distant background galaxies taken by the Subaru Telescope. Strands of dark matter can be seen extending millions of light years. Credit: HyeongHan et al.

The Subaru Telescope has spotted the terminal ends of dark matter filaments in the Coma Cluster stretching across millions of light years. This is the first time that strands of the cosmic web spanning the entire Universe have been directly detected. This provides new evidence to test theories about the evolution of the Universe.

In the Solar System we are used to seeing matter gathered into round objects like planets, moons, and the Sun. But dark matter, which accounts for most of the mass in the Universe, is believed to exist as a web of long thin strands. But like a spider web, these strands can be hard to see, so astronomers have typically drawn conclusions based on observations of galaxies and gas stuck in the web. This is similar to how if you see a dead leaf that appears to hang in midair, you know there is a spider web that you cannot see.

A team of researchers from Yonsei University used the Subaru Telescope to look for direct signs of dark matter filaments in the Coma Cluster, located 321 million light-years away in the direction of the constellation Coma Berenices. The Coma Cluster is one of the largest and closest galaxy clusters, making it a good place to look for faint signs of dark matter. Ironically, because it is so close, it also appears large, making it difficult to observe the entire cluster. The Subaru Telescope offers the right combination of high sensitivity, high resolution, and wide field of view, to make these observations possible. Through robust data analysis, the team identified the terminal segments of the invisible dark matter filaments attached to the Coma Cluster. This is the first time these strands have been confirmed directly, giving new evidence for the idea that dark matter webs stretch across the Universe.

These results appeared as HyeongHan et al. "Weak-lensing detection of intracluster filaments in the Coma cluster" in Nature Astronomy on January 5, 2024.

This research is based on data collected at Subaru Telescope and obtained from SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan.




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About the Subaru Telescope

The Subaru Telescope is a large optical-infrared telescope operated by the National Astronomical Observatory of Japan, National Institutes of Natural Sciences with the support of the MEXT Project to Promote Large Scientific Frontiers. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawai`i.