Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA.
Science. 2011 Mar 25;331(6024):1576-9. doi: 10.1126/science.1200331.
Studies of the diffuse x-ray-emitting gas in galaxy clusters have provided powerful constraints on cosmological parameters and insights into plasma astrophysics. However, measurements of the faint cluster outskirts have become possible only recently. Using data from the Suzaku x-ray telescope, we determined an accurate, spatially resolved census of the gas, metals, and dark matter out to the edge of the Perseus Cluster. Contrary to previous results, our measurements of the cluster baryon fraction are consistent with the expected universal value at half of the virial radius. The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web.
对星系团中弥漫的 X 射线发射气体的研究为宇宙学参数提供了有力的限制，并深入了解了等离子体天体物理学。然而，最近才有可能对微弱的星系团外围进行测量。利用 Suzaku 号 X 射线望远镜的数据，我们准确地确定了到英仙座星系团边缘的气体、金属和暗物质的空间分辨率普查。与之前的结果相反，我们对星系团重子分数的测量结果与半范体积处预期的普遍值一致。在更大的半径处，星系团的重子分数明显超过宇宙平均值，这表明气体的分布呈团块状，这对于理解星系团从周围宇宙网络中不断增长的过程非常重要。
