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arXiv 0705.4477astro-ph
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局域大尺度结构的未来:暗物质和暗能量的作用

The Future of the Local Large Scale Structure: the roles of Dark Matter and Dark Energy

Yehuda Hoffman, Ofer Lahav, Gustavo Yepes, Yaniv Dover

摘要:

我们使用约束N体模拟研究了暗物质和暗能量对附近大尺度结构未来演化的不同影响。我们对比了冷暗物质和宇宙学常数(LCDM)模型与开放CDM(OCDM)模型,其中物质密度Omega_m =0.3,哈勃常数h=0.7。当比例因子增加到6倍时(LCDM中从现在起为29 Gyr; OCDM中从现在起为78 Gyr),本星系团的共动位置已经被冻结。在那个纪元之前,本星系群中两个最大的成员,银河系和仙女座星系,将合并。然而,由于两个模型中比例因子的膨胀率不同,在LCDM模型中,本星系群将以指数方式从室女座的物理坐标中后退,而在OCDM模型中,本星系群将以大致恒定的速度后退。更一般地说,在同向运动坐标系中,未来的大尺度结构看起来将像是当前结构的一个锐化图像:宇宙网的骨架将保持不变,但星系团将更加“孤立”,细丝将变得更薄。这意味着在同动坐标系中看到的大尺度结构的长期命运主要由物质密度决定。我们的结论是,虽然LCDM模型由于其暗能量成分的存在,目前是加速的,而OCDM模型是非加速的,但它们未来的大尺度结构在共动坐标下看起来非常相似。

英文摘要:

We study the distinct effects of Dark Matter and Dark Energy on the future evolution of nearby large scale structures using constrained N-body simulations. We contrast a model of Cold Dark Matter and a Cosmological Constant (LCDM) with an Open CDM (OCDM) model with the same matter density Omega_m =0.3 and the same Hubble constant h=0.7. Already by the time the scale factor increased by a factor of 6 (29 Gyr from now in LCDM; 78 Gyr from now in OCDM) the comoving position of the Local Group is frozen. Well before that epoch the two most massive members of the Local Group, the Milky Way and Andromeda, will merge. However, as the expansion rates of the scale factor in the two models are different, the Local Group will be receding in physical coordinates from Virgo exponentially in a LCDM model and at a roughly constant velocity in an OCDM model. More generally, in comoving coordinates the future large scale structure will look like a sharpened image of the present structure: the skeleton of the cosmic web will remain the same, but clusters will be more `isolated' and the filaments will become thinner. This implies that the long-term fate of large scale structure as seen in comoving coordinates is determined primarily by the matter density. We conclude that although the LCDM model is accelerating at present due to its Dark Energy component while the OCDM model is non accelerating, their large scale structure in the future will look very similar in comoving coordinates.

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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