SUZAKU OBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE
SUZAKU OBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE
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DOI：
10.1088/0004-637x/714/1/423
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发表时间：
2010-02
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通讯作者：
M. Kawaharada;N. Okabe;K. Umetsu;M. Takizawa;K. Matsushita;Y. Fukazawa;T. Hamana;S. Miyazaki
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作者：
M. Kawaharada;N. Okabe;K. Umetsu;M. Takizawa;K. Matsushita;Y. Fukazawa;T. Hamana;S. Miyazaki
我们展示了对A1689星系团内介质（ICM）进行的新的、深入的Suzaku x射线观测（160 ks）的结果，并结合了从SDSS目录中获得的预测星系分布的互补数据集，以及我们最近对斯巴鲁/ supme - cam和哈勃太空望远镜/高级巡天相机观测结果进行的综合弱透镜和强透镜分析得出的预测质量分布。在维里半径（rvir ~ 15）附近的ICM发出的微弱x射线。’6)在4.0σ显著性下被检测到，这得益于Suzaku低而稳定的粒子背景。Suzaku观测揭示了星系团外围r500 > r > rvir的各向异性气体温度和熵分布与星系团周围光度红移片上星系的大尺度结构相关。东北（NE）外围的高温（~ 5.4 keV）和熵区显然与星系团外星系的过密丝状结构有关。NE方向的气体温度和熵分布与最近的XMM-Newton统计研究和ICM的吸积冲击加热模型的预测结果一致，达到了病毒半径。相反，与低密度空洞环境接触的其他外围区域具有较低的气体温度（~ 1.7 keV）和熵，偏离流体静力平衡。这些各向异性的ICM特征与大尺度结构环境有关，表明ICM的热化在过密的丝状结构上比在低密度的空洞区域上发生得更快。我们发现ICM的密度分布是相当各向同性的，在r2500≥r≤r500的径向范围内，密度斜率为−2.29±0.18，在r500≥r≤rvir的径向范围内，密度斜率为−1.24±0.23−0.56，但在外围ρ∝r−3的范围内，密度斜率明显小于Navarro、Frenk和White的普遍物质密度曲线。x射线和透镜联合分析表明，流体静力质量低于球透镜质量（~ 60% ~ 90%），但在误差范围内与三轴光晕质量相当，中间半径为0.6r2500 > r > 0.8r500。另一方面，无论何种质量模型，0.4r2500范围内的静压质量偏差均显著低至≤60%。r500内的热气体压力最多为总压力的~ 50%-60%，以完全平衡球透镜质量的重力，在viri半径周围为~ 30%-40%。虽然当考虑到可能的光晕三轴性时，这些构成了下限，但这些小的相对热压力贡献将需要额外的压力来源，如体积和/或湍流运动。
We present results of new, deep Suzaku X-ray observations (160 ks) of the intracluster medium (ICM) in A1689 out to its virial radius, combined with complementary data sets of the projected galaxy distribution obtained from the SDSS catalog and the projected mass distribution from our recent comprehensive weak and strong lensing analysis of Subaru/Suprime-Cam and Hubble Space Telescope/Advanced Camera for Surveys observations. Faint X-ray emission from the ICM around the virial radius (rvir ∼ 15.′6) is detected at 4.0σ significance, thanks to the low and stable particle background of Suzaku. The Suzaku observations reveal anisotropic gas temperature and entropy distributions in cluster outskirts of r500 ≲ r ≲ rvir correlated with large-scale structure of galaxies in a photometric redshift slice around the cluster. The high temperature (∼5.4 keV) and entropy region in the northeastern (NE) outskirts is apparently connected to an overdense filamentary structure of galaxies outside the cluster. The gas temperature and entropy profiles in the NE direction are in good agreement, out to the virial radius, with that expected from a recent XMM-Newton statistical study and with an accretion shock heating model of the ICM, respectively. On the contrary, the other outskirt regions in contact with low-density void environments have low gas temperatures (∼1.7 keV) and entropies, deviating from hydrostatic equilibrium. These anisotropic ICM features associated with large-scale structure environments suggest that the thermalization of the ICM occurs faster along overdense filamentary structures than along low-density void regions. We find that the ICM density distribution is fairly isotropic, with a three-dimensional density slope of −2.29 ± 0.18 in the radial range of r2500 ≲ r ≲ r500, and with −1.24+0.23−0.56 in r500 ≲ r ≲ rvir, which, however, is significantly shallower than the Navarro, Frenk, and White universal matter density profile in the outskirts, ρ ∝ r−3. A joint X-ray and lensing analysis shows that the hydrostatic mass is lower than the spherical-lensing one (∼60%–90%), but comparable to a triaxial halo mass within errors, at intermediate radii of 0.6r2500 ≲ r ≲ 0.8r500. On the other hand, the hydrostatic mass within 0.4r2500 is significantly biased as low as ≲60%, irrespective of mass models. The thermal gas pressure within r500 is, at most, ∼50%–60% of the total pressure to balance fully the gravity of the spherical-lensing mass, and ∼30%–40% around the virial radius. Although these constitute lower limits when one considers the possible halo triaxiality, these small relative contributions of thermal pressure would require additional sources of pressure, such as bulk and/or turbulent motions.