摘要 数值模拟技术不仅帮助我们确立了以暗物质、暗能量为主导的LCDM(Λcold dark matter)标准宇宙学模型,也帮助我们对暗物质形成的结构体——暗晕的各种属性给出了精细的刻画,特别是暗物质晕的密度轮廓.本文首先回顾了这一领域自20世纪80年代以来的发展历史.通过数值模拟,人们发现,暗晕密度轮廓并非理论模型预测的单一幂律分布,而是从内向外,幂指数从-1左右到-3逐渐变化;而且,暗晕的内部结构由其形成历史决定.此后,人们逐步对100万太阳质量以上暗晕的内部结构有了非常精准的刻画.但由于计算资源的限制,对比这一质量小的暗晕则依然了解甚少.最近通过新开发的多重模拟技术,我们才得以对从最小的地球大小的暗晕(10-6太阳质量)到最大的星系团暗晕(1015太阳质量)的内部结构给出精确描述.本文对这一重要进展进行了详细的解读.总之,对所有质量暗晕的密度轮廓的认识将会帮助我们理解物质在宇宙中的分布、暗晕形成在星系形成过程中的作用,同时也将帮助我们去探索如何更好地通过天体物理方法来确定暗物质的本质属性,但重子物质的各种复杂物理过程对暗晕内部结构,特别是密度轮廓的影响依然还是一个开放的问题,这也将是我们下一步需要研究的主要方向. Numerical simulations play important role in estimation of the LCDM(Λcold dark matter)model as the standard cosmological model in which dark matter and dark energy are the main driving force in the universe.It also helps us to understand the various properties of dark matter halo,especially the density profile in the haloes.In this article,we will review the progress on this issue since 1980 s.By virtue of N-body simulation,we know that the density profiles of dark matter haloes are not exactly following a single power law as what the theoretical model predicted.Instead the power index of the density profile is gradually changing from-1 inside to-3 outside.Furthermore,the density profile is determined by halo’s mass assembly history and the initial power spectrum of the cosmic density field.With efforts in the past forty years,we have known well the internal structure of haloes with mass greater than 106 solar mass,however we know less on that with mass less than this scale because of the limit of computational resources.In the second part of this article,we will review a highlight research on this issue recently.With a new multi-level zooming technic,Wang et al simulate the formation of present-day haloes over the full range of observed halo masses(20 orders of magnitude)in a cosmological framework.Here dark matter is assumed to be in the form of weakly interacting massive particles of mass approximately 100 GeV.This series of simulations help to resolve the internal structure of hundreds of Earth-mass haloes in as much detail as it does for hundreds of rich galaxy clusters.In this cosmic zoom simulation,the density profile over the whole mass range could be described by a two parameter fitting formulae very well.The concentration of these haloes gets decreased with the decreasing of the halo mass.An accurate fitting function for the mass concentration relation in the whole mass range is provided.With the knowledge of the density profile of all dark matter haloes,we could understand how the mass is distribute
出处 《科学通报》 EI CAS CSCD 北大核心 2021年第11期1327-1335,共9页 Chinese Science Bulletin
基金 国家自然科学基金(11988101,11373029,11873051)资助。
关键词 暗物质 暗晕 暗物质探测 宇宙学 数值模拟 N体模拟 dark matter dark halo dark matter detection cosmology numerical simulation N-body
分类号 P14 [天文地球—天体物理]
