The state of the hot gas in clusters of galaxies is investigated with a set of model clusters, created by assuming a polytropic equation of state (Gamma=1.2) and hydrostatic equilibrium inside gravitational potential wells drawn from a dark matter simulation. Star formation, energy input, and nonthermal pressure support are included. To match the gas fractions seen in non-radiative hydrodynamical simulations, roughly 5% of the binding energy of the dark matter must be transferred to the gas during cluster formation; the presence of nonthermal pressure support increases this value. In order to match X-ray observations, scale-free behavior must be broken. This can be due to either variation of the efficiency of star formation with cluster mass M_500, or the input of additional energy proportional to the formed stellar mass M_F. These two processes have similar effects on X-ray scalings. If 9% of the gas is converted into stars, independent of cluster mass, then feedback energy input of 1.2e-5*M_Fc^2 (or ~1.0 keV per particle) is required to match observed clusters. Alternatively, if the stellar mass fraction varies as M_500^-0.26 then a lower feedback of 4e-6*M_Fc^2 is needed, and if the stellar fraction varies as steeply as M_500^-0.49 then no additional feedback is necessary. The model clusters reproduce the observed trends of gas temperature and gas mass fraction with cluster mass, as well as observed entropy and pressure profiles; thus they provide a calibrated basis with which to interpret upcoming SZ surveys. One consequence of the increased gas energy is that the baryon fraction inside the virial radius is less than roughly 90% of the cosmic mean, even for the most massive clusters.
Intracluster Light as a Probe for Dark Matter: Exploring Self-interacting Dark Matter and Cold Dark Matter with C-EAGLE Sims
Korea Astronomy and Space Science Institute (KASI)（韩国天文学与空间科学研究所）；Quantum Universe Center, Korea Institute for Advanced Study（量子宇宙中心，韩国高等研究院）；School of Physics, The University of Sydney（悉尼大学物理学院）；ARC Centre of Excellence for Dark Matter Particle Physics（暗物质粒子物理卓越研究中心）；Departamento de Física Teórica, Facultad de Ciencias M-8, Universidad Autónoma de Madrid（马德里自治大学理学院M-8理论物理系）；Natural Science Research Institute (NSRI), University of Seoul（首尔大学自然科学研究所）；School of Physics, Korea Institute for Advanced Study（韩国高等研究院物理学院）；School of Physics and Astronomy, University of Nottingham（诺丁汉大学物理与天文学院）；Center for Advanced Computation, Korea Institute for Advanced Study（韩国高等研究院先进计算中心）；University of Science and Technology (UST)（科学技术院）
A large thermal energy reservoir in the nascent intracluster medium at a redshift of 4.3
University of British Columbia（不列颠哥伦比亚大学）；Dalhousie University（达尔豪斯大学）；National Research Council, Herzberg Astronomy and Astrophysics（国家研究委员会赫茨伯格天文学与天体物理学研究所）；Universidad Diego Portales（迭戈帕托莱斯大学）；Universidade de São Paulo（圣保罗大学）；University of Chicago（芝加哥大学）；University of Florida（佛罗里达大学）；University of the Witwatersrand（威特沃特斯兰德大学）；University of Pretoria（比勒陀利亚大学）
Discovery of a nearby radio relic in the low-mass, merging cluster Abell 4067
University of the Witwatersrand（威特沃特斯兰德大学）；University of Pretoria（比勒陀利亚大学）；SKA Observatory（平方公里阵列射电望远镜天文台）；University of Oxford（牛津大学）；Rhodes University（罗兹大学）；South African Radio Astronomy Observatory（南非射电天文观测站）；Texas A&M University（德克萨斯农工大学）；Chulalongkorn University（朱拉隆功大学）
Exploring a Cosmic-Ray Inverse-Compton Origin to the SZ-to-X-Ray Pressure Deficit in the Cool Core Cluster ZwCl 3146
California Institute of Technology（加州理工学院）；University of Pennsylvania（宾夕法尼亚大学）；National Radio Astronomy Observatory（美国国家射电天文台）；University of Virginia（弗吉尼亚大学）
