Universal profiles of the intracluster medium from Suzaku X-ray and Subaru weak-lensing observations
Universal profiles of the intracluster medium from Suzaku X-ray and Subaru weak-lensing observations
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DOI：
10.1093/pasj/psu075
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发表时间：
2014-06
影响因子：
2.3
通讯作者：
N. Okabe;K. Umetsu;T. Tamura;Y. Fujita;M. Takizawa;Y. Zhang;K. Matsushita;T. Hamana;Y. Fukazawa;T. Futamase;M. Kawaharada;S. Miyazaki;Y. Mochizuki;K. Nakazawa;T. Ohashi;N. Ota;T. Sasaki;K. Sato;S. Tam
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作者：
N. Okabe;K. Umetsu;T. Tamura;Y. Fujita;M. Takizawa;Y. Zhang;K. Matsushita;T. Hamana;Y. Fukazawa;T. Futamase;M. Kawaharada;S. Miyazaki;Y. Mochizuki;K. Nakazawa;T. Ohashi;N. Ota;T. Sasaki;K. Sato;S. Tam
我们对朱雀和斯巴鲁观测到的四个弛豫星系团（Hydra A，A478，A1689和A1835）进行了X射线和弱透镜联合研究，目的是了解最近发现的星系团外围ICM的意外特征。结果表明，随着超密度对比度从500减小到维里值，四个星系团的平均流体静力-透镜总质量比从70%减小到40%，由透镜总质量估算的平均气体质量分数随星系团半径的增大而增大，并与维里半径内的宇宙平均重子分数一致，而基于X射线的气体部分由于低估了流体静力质量而大大超过了宇宙值。我们还开发了一种新的先进的方法，同时考虑到他们的径向依赖性和多变量的标度关系与弱透镜质量确定归一化集群径向配置文件的多个X射线观测。虽然这四个星系团的晕质量、浓度、X射线光度和红移都在一定范围内，但我们发现，当以M_200质量和半径r_200为尺度时，气体熵、压力、温度和密度分布都具有显著的自相似性，熵随吸积激波加热模型K（r）\propto r^1.1单调增加到\sim 0.5r_200，标度熵分布的普适性表明，整个团簇区域的热化机制（>0.1r_200）是由引力控制的，这是所有星系团的共同点，虽然在郊区的加热效率需要从标准定律修正.气体密度和温度的双变量标度函数揭示边缘熵分布的平坦化是由温度的陡化引起的，而不是由气体密度的平坦化引起的。
We conduct a joint X-ray and weak-lensing study of four relaxed galaxy clusters (Hydra A, A478, A1689 and A1835) observed by both Suzaku and Subaru out to virial radii, with an aim to understand recently-discovered unexpected feature of the ICM in cluster outskirts. We show that the average hydrostatic-to-lensing total mass ratio for the four clusters decreases from \sim 70% to \sim 40% as the overdensity contrast decreases from 500 to the virial value.The average gas mass fraction from lensing total mass estimates increases with cluster radius and agrees with the cosmic mean baryon fraction within the virial radius, whereas the X-ray-based gas fraction considerably exceeds the cosmic values due to underestimation of the hydrostatic mass. We also develop a new advanced method for determining normalized cluster radial profiles for multiple X-ray observables by simultaneously taking into account both their radial dependence and multivariate scaling relations with weak-lensing masses. Although the four clusters span a range of halo mass, concentration, X-ray luminosity and redshift, we find that the gas entropy, pressure, temperature and density profiles are all remarkably self-similar when scaled with the lensing M_200 mass and r_200 radius.The entropy monotonically increases out to \sim 0.5r_200 following the accretion shock heating model K(r)\propto r^1.1, and flattens at \simgt 0.5r_200.The universality of the scaled entropy profiles indicates that the thermalization mechanism over the entire cluster region (>0.1r_200) is controlled by gravitation in a common to all clusters, although the heating efficiency in the outskirts needs to be modified from the standard law.The bivariate scaling functions of the gas density and temperature reveal that the flattening of the outskirts entropy profile is caused by the steepening of the temperature, rather than the flattening of the gas density.