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外文期刊>The Astrophysical journal
>SUZAKU OBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE
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SUZAKU OBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE
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 (r vir ~ 156) 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 r 500 r r vir 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 r 2500 r r 500, and with –1.24+0.23 –0.56 in r 500 r r vir, 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 0.6r 2500 r 0.8r 500. On the other hand, the hydrostatic mass within 0.4r 2500 is significantly biased as low as 60%, irrespective of mass models. The thermal gas pressure within r 500 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.
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机译：我们介绍了A1689中簇内介质（ICM）的新深层朱雀X射线观测结果（160？ks）到其病毒半径，并结合了从SDSS目录获得的预计星系分布的补充数据集和预计的我们最近对Subaru / Suprime-Cam和Hubble太空望远镜/高级观测相机进行的综合弱透镜和强透镜分析得出的质量分布。由于朱雀的低而稳定的粒子背景，ICM在病毒半径（r vir〜156）附近发出的微弱X射线被检测为4.0σ的显着性。 Suzaku的观测揭示了r 500 r r vir团簇郊区的各向异性气体温度和熵分布，与团簇周围的光度红移片中的星系的大规模结构有关。东北（NE）郊区的高温（〜5.4？keV）和熵区显然与星团外星系的过度丝状结构有关。 NE方向的气体温度和熵分布与病毒半径基本吻合，分别与最近的XMM-Newton统计研究和ICM的积聚激振加热模型所期望的一样。相反，与低密度孔隙环境接触的其他郊区区域具有较低的气体温度（〜1.7？keV）和熵，从而偏离了静水平衡。这些与大规模结构环境相关的各向异性ICM特征表明，ICM的热化沿稠密丝状结构的发生比沿低密度空隙区域的发生快。我们发现ICM密度分布是各向同性的，在r 2500 rr 500的径向范围内，三维密度斜率为–2.29±0.18，在r 500 rr vir中的三维密度斜率为–1.24 + 0.23 –0.56，但是， ，比郊外的纳瓦罗，弗兰克和怀特普遍物质密度剖面ρ∝ r –3浅得多。 X射线和透镜联合分析表明，静水压质量低于球形透镜的静水质量（〜60％-90％），但在误差为中间值0.6r 2500 r 0.8r时，可与三轴晕质量相媲美。 500.另一方面，无论质量模型如何，0.4r 2500内的静水质量都会明显偏低至60％。 r 500内的热气体压力最多为总压力的〜50％-60％，以完全平衡球形透镜的引力，而在径向半径附近则为〜30％-40％。尽管当考虑可能的光晕三轴性时，这些构成较低的限制，但是，这些较小的热压力相对贡献将需要其他压力源，例如体积和/或湍流运动。
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