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arXiv 1504.04025astro-ph.GAastro-ph.CO
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在EAGLE和cosmo-OWLS模拟中暗物质、恒星和热气分布的排列和形状

The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations

Marco Velliscig, Marcello Cacciato, Joop Schaye, Robert A. Crain, Richard G. Bower, Marcel P. van Daalen, Claudio Dalla Vecchia, Carlos S. Frenk, Michelle Furlo… 展开作者

Marco Velliscig, Marcello Cacciato, Joop Schaye, Robert A. Crain, Richard G. Bower, Marcel P. van Daalen, Claudio Dalla Vecchia, Carlos S. Frenk, Michelle Furlong, Ian G. McCarthy, Matthieu Schaller, Tom Theuns

摘要:

我们报告的暗物质,恒星和热气体分布在EAGLE和cosmo-OWLS模拟的对齐和形状。结合这些最先进的水文宇宙学模拟,使我们能够跨越四个数量级的晕质量($11 < log_{10}(M_{200}/ [h^{-1}M_\odot]) < 15$),一个广泛的径向范围($-2.3 < log_{10}(r/[h^{-1}Mpc ]) < 1.3$)和红移$0 < z < 1$。暗物质、恒星和热气体分布的形状参数遵循定性相似的趋势:随着晕质量、半径和红移的增加,它们变得更加非球面(和三轴)。我们测量的重子组件(热气体和恒星)的星系与其主机晕作为晕质量,半径,红移和星系类型(中心与卫星和早期与晚期型)的函数的错位。总的来说,星系与总物质(主要是暗物质)的局部分布很好地对齐。然而,星系尺度上的恒星分布相对于它们的宿主晕呈现出大约45 - 50度的中位失准。在质量最大的晕($13 < log_{10}(M_{200}/ [h^{-1}M_\odot ]) < 15$)中,这种不对准减小到25 - 30度。在EAGLE模拟中,有一半的盘星系相对于其宿主晕的失准角大于40度。我们提出的拟合函数和列表值的概率分布的星系晕错位,使我们的结果直接列入模型的星系形成的基础上纯粹的碰撞N体模拟。

英文摘要:

We report the alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations. The combination of these state-of-the-art hydro-cosmological simulations enables us to span four orders of magnitude in halo mass ($11 < log_{10}(M_{200}/ [h^{-1}M_\odot]) < 15$), a wide radial range ($-2.3 < log_{10}(r/[h^{-1}Mpc ]) < 1.3$) and redshifts $0 < z < 1$. The shape parameters of the dark matter, stellar and hot gas distributions follow qualitatively similar trends: they become more aspherical (and triaxial) with increasing halo mass, radius and redshift. We measure the misalignment of the baryonic components (hot gas and stars) of galaxies with their host halo as a function of halo mass, radius, redshift, and galaxy type (centrals vs satellites and early- vs late-type). Overall, galaxies align well with the local distribution of the total (mostly dark) matter. However, the stellar distributions on galactic scales exhibit a median misalignment of about 45-50 degrees with respect to their host haloes. This misalignment is reduced to 25-30 degrees in the most massive haloes ($13 < log_{10}(M_{200}/ [h^{-1}M_\odot ]) < 15$). Half of the disc galaxies in the EAGLE simulations have a misalignment angle with respect to their host haloes larger than 40 degrees. We present fitting functions and tabulated values for the probability distribution of galaxy-halo misalignment to enable a straightforward inclusion of our results into models of galaxy formations based on purely collisionless N-body simulations.

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