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}} The Phoenix Cluster (SPT-CL J2344-4243) is a massive, type I galaxy cluster located at its namesake constellation, the southern constellation of Phoenix. It is one of the most massive galaxy clusters known, with the mass on the order of 2 .〔 Another cluster, El Gordo, also in Phoenix, is slightly more massive. Most of the mass of the Phoenix Cluster is in the form of dark matter and its intracluster medium. The central elliptical cD galaxy of this cluster is undergoing a massive starburst, the highest recorded in a middle of a galaxy cluster, although other galaxies at higher redshifts have a higher starburst rate (see Baby Boom Galaxy). 〔Min Yun et al.; "Deep 1.1 mm-wavelength imaging of the GOODS-South field by AzTEC/ASTE – II. Redshift distribution and nature of the submillimetre galaxy population", arXiv, 28 September 2011, 〕 Observations by a variety of telescopes including the GALEX and Herschel space telescopes shows that it has been converting material to stars at an exceptionally astonishing rate of 740 per year.〔 This is considerably higher than that of NGC 1275 A, the central galaxy of the Perseus Cluster, where stars are formed at a rate around 20 times lower, or the one per year rate of star formation in the Milky Way. Not only is the central galaxy notable for its starburst rate, but also for its size. The vast stellar halo of the Phoenix Cluster central galaxy extends to over 1.1 million light years from the center, making it one of the largest galaxies known. It is 22 times the diameter of the Milky Way, and its starburst activity suggests that the galaxy is still growing larger. This states that what we're witnessing from the central galaxy is the evolution of one of the largest and most massive galaxies in the universe. Phoenix Cluster is also producing more X-rays than any other known massive cluster.〔 The central galaxy in the cluster contains vast amounts of hot gas. More normal matter is present there than the total of all the other galaxies in the cluster. Data from observations indicate that hot gas is cooling in the central regions at a rate of 3,820 solar masses per year, the highest ever recorded.〔 The central cD galaxy of the cluster hosts an active galactic nucleus, which is powered by a central supermassive black hole like those of other galaxies. But the central black hole is devouring matter and is continuously growing at a rate of 60 every year. The central black hole has an estimated mass of on the order of 20 billion .〔 This makes it one of the most massive black holes known in the universe, 5,000 times the mass of the black hole at the center of the Milky Way. The diameter of the black hole's immense event horizon is on the order of 118 billion kilometres, 19 times the distance from the Sun to Pluto, and has the mass equivalent to that of two dwarf galaxies. The Phoenix Cluster was initially detected using the Sunyaev–Zel'dovich effect by the South Pole Telescope collaboration.〔 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phoenix Cluster」の詳細全文を読む スポンサード リンク
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