Projected alignment of non-sphericities of stellar, gas, and dark matter distributions in galaxy clusters: analysis of the Horizon-AGN simulation
Projected alignment of non-sphericities of stellar, gas, and dark matter distributions in galaxy clusters: analysis of the Horizon-AGN simulation
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DOI：
10.1093/mnras/sty1068
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发表时间：
2018-04
影响因子：
4.8
通讯作者：
T. Okabe;T. Nishimichi;M. Oguri;S. Peirani;T. Kitayama;S. Sasaki;Y. Suto
中科院分区：
文献类型：
--
作者：
T. Okabe;T. Nishimichi;M. Oguri;S. Peirani;T. Kitayama;S. Sasaki;Y. Suto
虽然各种观测测量了星系团的椭圆率，以及最亮星系团与其主星系团的方向之间的排列，但只有少数数值模拟实现了现实的重子物理，以便与这些观测进行直接比较。在这里，我们在最先进的宇宙流体动力学模拟Horizon-AGN中研究了星系团的椭圆率及其各组成部分与中心星系之间的排列，该模拟箱包含暗物质，恒星和气体成分，位于$(100 h^{-1}$ Mpc $)^3$的大型模拟箱中，具有高空间分辨率（$\sim1$ kpc）。我们估计了总物质、暗物质、恒星、气体表面质量密度分布、x射线表面亮度、Sunyaev-Zel'dovich效应的康普顿$y$参数的椭圆率，以及120张质量为$M_{200}>5\times10^{13}M_{\odot}$的星系团投影图像中这些成分与中心星系之间的排列。我们的结果表明，这些成分的分布与中心星系的长轴很好地对齐，它们的位置角度差的均方根值为$\sim 20^\circ$，从内部到外部区域变化不大。我们还估计了这些不同成分与总物质分布的排列，并发现比均方根值为$\sim 15^\circ$的中心星系更紧密的排列。我们将我们的结果与先前的椭圆度和位置角对齐的观测结果进行了比较，并找到了合理的一致性。本文提出的综合分析为分析叠加透镜信号以及设计未来观测来研究星系团的椭圆和排列提供了有用的先验信息。
While various observations measured ellipticities of galaxy clusters and alignments between orientations of the brightest cluster galaxies and their host clusters, there are only a handful of numerical simulations that implement realistic baryon physics to allow direct comparisons with those observations. Here we investigate ellipticities of galaxy clusters and alignments between various components of them and the central galaxies in the state-of-the-art cosmological hydrodynamical simulation Horizon-AGN, which contains dark matter, stellar, and gas components in a large simulation box of $(100 h^{-1}$ Mpc$)^3$ with high spatial resolution ($\sim1$ kpc). We estimate ellipticities of total matter, dark matter, stellar, gas surface mass density distributions, X-ray surface brightness, and the Compton $y$-parameter of the Sunyaev-Zel'dovich effect, as well as alignments between these components and the central galaxies for 120 projected images of galaxy clusters with masses $M_{200}>5\times10^{13}M_{\odot}$. Our results indicate that the distributions of these components are well aligned with the major-axes of the central galaxies, with the root mean square value of differences of their position angles of $\sim 20^\circ$, which vary little from inner to the outer regions. We also estimate alignments of these various components with total matter distributions, and find tighter alignments than those for central galaxies with the root mean square value of $\sim 15^\circ$. We compare our results with previous observations of ellipticities and position angle alignments and find reasonable agreements. The comprehensive analysis presented in this paper provides useful prior information for analyzing stacked lensing signals as well as designing future observations to study ellipticities and alignments of galaxy clusters.