A Clash of Clusters
A powerful collision of galaxy clusters has been captured by NASA's Hubble Space Telescope and Chandra X-ray Observatory. This clash of clusters provides striking evidence for dark matter and insight into its properties.
The observations of the cluster known as MACS J0025.4-1222 indicate that a titanic collision has separated the dark from ordinary matter and provide an independent confirmation of a similar effect detected previously in a target dubbed the Bullet Cluster. These new results show that the Bullet Cluster is not an anomalous case.
MACS J0025 formed after an enormously energetic collision between two large clusters. Using visible-light images from Hubble, the team was able to infer the distribution of the total mass -- dark and ordinary matter. Hubble was used to map the dark matter (colored in blue) using a technique known as gravitational lensing. The Chandra data enabled the astronomers to accurately map the position of the ordinary matter, mostly in the form of hot gas, which glows brightly in X-rays (pink).
As the two clusters that formed MACS J0025 (each almost a quadrillion times the mass of our sun) merged at speeds of millions of miles per hour, the hot gas in the two clusters collided and slowed down, but the dark matter passed right through the smashup. The separation between the material shown in pink and blue therefore provides observational evidence for dark matter and supports the view that dark-matter particles interact with each other only very weakly or not at all, apart from the pull of gravity.
Image Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University)
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銀河団の衝突
銀河団の強烈な衝突をNASAのハッブル宇宙望遠鏡およびチャンドラX線観測装置が捉えた。
この衝突は暗黒物質の存在を示唆している。
ハッブルは重力レンズを使って暗黒物質をマッピングした（ブルーの部分）、チャンドラのデータから通常物質をマッピングした。通常物質の大半は明るく輝く熱いガスである（ピンクの部分）
ピンクとブルー部分に分離していることが、暗黒物質の存在の証拠である。
ふたつの星団が交じり合うとき、ふたつの星団の熱いガスはぶつかりながらスローダウンして行くが、引力圏から離れた暗黒物質の粒子はかすかに反応するだけである・・・
そして、暗黒物質は消え行く・・・
摩訶不思議な示唆である、、、謎のようで、謎ではない・・・
Aoyagi YoSuKe
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