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Planck spots hot gas bridging galaxy clusters

The European Space Agency’s space telescope has spotted an extraordinary scene: A bridge of hot gas linking a pair of galaxy clusters across 10 million light-years of intergalactic space.

According to the ESA, the Planck space telescope’s primary mission is to capture the oldest light of the Cosmic Microwave Background (CMB). As this light moves across the Universe, it runs into galaxies and galaxy clusters.

The ESA says that if the CMB light engages with the hot gas spreading through these massive cosmic structures, its energy is changed in a unique way, an event called the Sunyaev–Zel’dovich (SZ) effect, named after the scientists who came across it.

The ESA notes that SZ effect has already been utilized by Planck to find galaxy clusters themselves, but it can also be used as a way to find faint strands of gas bridging galaxy clusters.

The space agency says that strands of gaseous matter spread throughout the early Universe in a large web. Although a lot of this gaseous matter is still undetected, astronomers believe that it could most likely be discovered between interacting galaxy clusters.

When the galaxy clusters interact, the strands heat up and compress, allowing them to be found. Planck’s uncovering of the clusters Abell 399 and Abell 401 is one example of how these filaments can spotted.

Although Planck data confirmed the hot gas bridging these galaxy clusters, the ESA says that the presence of the hot gas was first suggested by X-ray data gathered by the space agency’s XMM-Newton space telescope.

This is the first time, the ESA notes, that Planck has detected hot gas bridging a pair of galaxy cluster by deploying the SZ effect technique.

The ESA believes that the temperature of the gas is approximately 80 million degree Celsius (similar to the temperature of the gas in the two galaxy clusters). The bridging gas is most likely a combination of the hard-to-detect strands of the cosmic web and gas that comes from the galaxy clusters.

Astronomers hope to continue spotting hot gas bridging galaxy clusters, as each discovery will lead to more conclusive answers about the science behind the interaction between galaxy clusters.