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arXiv 0901.2938astro-ph.GAastro-ph.CO
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Milky Way中的暗物质盘

A dark matter disc in the Milky Way

J. I. Read, V. Debattista, O. Agertz, L. Mayer, A. M. Brooks, F. Governato, G. Lake

摘要:

预测暗物质粒子的局域通量对于暗物质直接探测实验至关重要。到目前为止,这些预测都是基于对暗物质的模拟。在这里,我们第一次把重子物质的影响包括在内。我们使用两种不同的方法。首先,我们使用暗物质的模拟来估计银河系质量星系的合并历史,然后添加一个薄的恒星盘来测量它的效果。其次,我们使用三个银河系质量星系的宇宙学流体动力学模拟。在这两种情况下,我们发现,恒星/气体盘在高红移(z~1)的合并卫星优先被拖向盘平面。这导致了一个吸积的暗物质盘,它贡献了太阳位置非旋转晕密度的0.25 - 1倍。一个与暗盘相关联的厚恒星盘形成,并共享类似的速度分布。如果这些吸积的恒星可以从原位形成的恒星中分离出来,未来的天文观测将能够从这些恒星中推断出暗盘的性质。与暗物质流不同,暗盘是一种平衡结构,必须存在于形成于等级宇宙学中的盘状星系中。它相对于地球的低旋转滞后显著增强了地球和太阳对WIMP的捕获,增加了在低反冲能量下直接检测的可能性,增强了年度调制信号,并导致通量作为反冲能量的函数的明显变化,从而可以确定WIMP质量(参见T. Bruch本卷)。

英文摘要:

Predicting the local flux of dark matter particles is vital for dark matter direct detection experiments. To date, such predictions have been based on simulations that model the dark matter alone. Here we include the influence of the baryonic matter for the first time. We use two different approaches. Firstly, we use dark matter only simulations to estimate the expected merger history for a Milky Way mass galaxy, and then add a thin stellar disc to measure its effect. Secondly, we use three cosmological hydrodynamic simulations of Milky Way mass galaxies. In both cases, we find that a stellar/gas disc at high redshift (z~1) causes merging satellites to be preferentially dragged towards the disc plane. This results in an accreted dark matter disc that contributes ~0.25 - 1 times the non-rotating halo density at the solar position. An associated thick stellar disc forms with the dark disc and shares a similar velocity distribution. If these accreted stars can be separated from those that formed in situ, future astronomical surveys will be able to infer the properties of the dark disc from these stars. The dark disc, unlike dark matter streams, is an equilibrium structure that must exist in disc galaxies that form in a hierarchical cosmology. Its low rotation lag with respect to the Earth significantly boosts WIMP capture in the Earth and Sun, increases the likelihood of direct detection at low recoil energy, boosts the annual modulation signal, and leads to distinct variations in the flux as a function of recoil energy that allow the WIMP mass to be determined (see contribution from T. Bruch this volume).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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