The universal galaxy cluster pressure profile from a representative sample of nearby systems (REXCESS) and the YSZ-M500 relation
The universal galaxy cluster pressure profile from a representative sample of nearby systems (REXCESS) and the YSZ-M500 relation
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DOI：
10.1051/0004-6361/200913416
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发表时间：
2010-07-01
影响因子：
6.5
通讯作者：
Pointecouteau, E.
中科院分区：
文献类型：
--
作者：
Arnaud, M.;Pratt, G. W.;Pointecouteau, E.
我们利用REXCESS研究了星团压力分布的规律性，REXCESS是来自REFLEX星表的33个局部（z < 0.2）星团的代表性样本，并利用XMM-Newton进行观测。样本的质量范围为10(14)M-Theta < M-500 < 10(15) M-Theta，其中M-500为密度对比500对应的质量。根据标准的自相似模型，我们从质量和红移的观测中得到了一个平均分布，并发现关于平均值的色散非常低，在0.2 R-500以上小于30%，但向中心增加。平均值的偏差与星团的质量和热力学状态有关。形态扰动系统具有系统的较浅剖面，而冷却堆芯系统更集中。缩放后的剖面表现出近似于0.12的残余质量依赖关系，与经验推导的M-500 - Y-X关系的斜率相一致；然而，偏离标准尺度随半径的减小而减小，在R-500时基本为零。与熵分布相比，核心的散射和偏离自相似的质量尺度较小，表明压力是受动力历史和非引力物理影响最小的量。与几个最先进的数值模拟的缩放数据进行比较，显示出核心外的良好一致性。结合径向范围[0.03-1]R-500的观测数据和径向范围[1-4]R-500的模拟数据，我们得出了一个可靠的通用压力分布测量方法，该方法以解析形式将星团的物理压力分布定义为质量和红移到星团“边界”的函数。利用该剖面和观测压力剖面的直接球面积分，我们估计了综合康普顿参数Y，并研究了其与M-500和L-X（软带x射线光度）的标度关系。我们考虑了与气体热能成正比的球面积分Y-sph(R)和与Sunyaev-Zel'dovich （SZ）效应信号直接相关的圆柱积分Y-cyl(R) = YSZD2A。从观测到的Y-sph(R-500)-Y-X关系的低散射来看，与Y-X-M-500关系相比，压力剖面形状的变化不会给Y-sph(R-500)-M-500关系带来额外的散射。由数据推导出的Y-sph(R-500)-M-500和Y-sph(R-500)-L-X关系与通用剖面的预测值非常吻合。该剖面可用于推导任意孔径下的Y-SZ - M-500和Y-SZ - L-X关系。
We investigate the regularity of cluster pressure profiles with REXCESS, a representative sample of 33 local (z < 0.2) clusters drawn from the REFLEX catalogue and observed with XMM-Newton. The sample spans a mass range of 10(14) M-Theta < M-500 < 10(15) M-Theta, where M-500 is the mass corresponding to a density contrast of 500. We derive an average profile from observations scaled by mass and redshift according to the standard self-similar model, and find that the dispersion about the mean is remarkably low, at less than 30 per cent beyond 0.2 R-500, but increases towards the center. Deviations about the mean are related to both the mass and the thermo-dynamical state of the cluster. Morphologically disturbed systems have systematically shallower profiles while cooling core systems are more concentrated. The scaled profiles exhibit a residual mass dependence with a slope of similar to 0.12, consistent with that expected from the empirically-derived slope of the M-500 - Y-X relation; however, the departure from standard scaling decreases with radius and is consistent with zero at R-500. The scatter in the core and departure from self-similar mass scaling is smaller compared to that of the entropy profiles, showing that the pressure is the quantity least affected by dynamical history and non-gravitational physics. Comparison with scaled data from several state of the art numerical simulations shows good agreement outside the core. Combining the observational data in the radial range [0.03-1] R-500 with simulation data in the radial range [1-4] R-500, we derive a robust measure of the universal pressure profile, that, in an analytical form, defines the physical pressure profile of clusters as a function of mass and redshift up to the cluster "boundary". Using this profile and direct spherical integration of the observed pressure profiles, we estimate the integrated Compton parameter Y and investigate its scaling with M-500 and L-X, the soft band X-ray luminosity. We consider both the spherically integrated quantity, Y-sph(R), proportional to the gas thermal energy, and the cylindrically integrated quantity, Y-cyl(R) = YSZD2A, which is directly related to the Sunyaev-Zel'dovich (SZ) effect signal. From the low scatter of the observed Y-sph(R-500)-Y-X relation we show that variations in pressure profile shape do not introduce extra scatter into the Y-sph(R-500)-M-500 relation as compared to that from the Y-X-M-500 relation. The Y-sph(R-500)-M-500 and Y-sph(R-500)-L-X relations derived from the data are in excellent agreement with those expected from the universal profile. This profile is used to derive the expected Y-SZ - M-500 and Y-SZ - L-X relations for any aperture.