Dwarf Galaxies and the Nature of Dark Matter

矮星系和暗物质的本质

• 批准号: RGPIN-2014-05647
• 负责人: Navarro, Julio
• 金额: $ 4.52万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588532
• 关键词: Dwarf; Galaxies; Nature; Dark; Matter

The past few decades have seen the emergence of a paradigm for the content and geometry of the Universe. This paradigm (usually referred to by its acronym LCDM) envisions the matter-energy content of the Universe as dominated by the evolving balance between radiation and two exotic components: cold dark matter and dark energy. However improbable this may sound, LCDM successfully accounts for most cosmological observations on large scales, and is widely regarded as the first successful cosmological theory ever devised. Its success on large scales notwithstanding, LCDM makes predictions on small scales that apparently run into conflict with observations of faint galaxies. These issues have surfaced as the completion of photometric and redshift surveys of large portions of the sky has revolutionized our understanding of faint galaxies, extending the inventory of dwarf galaxies to luminosities so faint that they blur the traditional distinction between galaxies and star clusters. These observations have highlighted potentially fatal challenges to LCDM on small scales, including the lack of a conspicuous “cusp” of dark matter at the center of dwarf galaxies; the scarcity of low-mass galaxies compared with the huge predicted abundance of low-mass dark matter halos capable, in principle, of hosting them; as well as oddities in the kinematic and spatial arrangement of the dwarf satellites of the Milky Way and Andromeda galaxies. All of these problems are the subject of active investigation, especially since plausible (but radical) modifications to the LCDM paradigm, such as “warm” or “self-interacting” dark matter, provide attractive alternatives. The confrontation of data with LCDM predictions for the smallest galaxies known thus holds the promise to validate or challenge the established paradigm on scales far removed from those used to tune its main parameters. The time seems ripe for a concerted effort designed to assess the cosmological significance of Nature's smallest extragalactic objects. I propose to study this topic using a variety of observational and theoretical tools, from detailed N-body simulation of the formation of dark matter halos, to gas-dynamical simulation of the formation of luminous dwarf galaxies, to direct observational efforts designed to survey the faintest galaxies in our Local Universe and to understand their impact on the formation of our Milky Way galaxy.

过去几十年来，宇宙内容和几何形状的出现了。这种范式（通常由其首字母缩写LCDM提到）设想了宇宙的物质能量含量是由辐射和两个异国情调组成部分之间不断发展的平衡所占据的：冷暗物质和深色能量。但是，这听起来可能是LCDM成功地解释了大多数宇宙学上的观察结果，并被广泛认为是有史以来第一个成功的宇宙学理论。尽管在很大的范围内，LCDM还是在很大的规模上进行了预测，这显然与公平星系的观察陷入了冲突。这些问题已经浮出水面，因为对大部分天空的光度和红移调查的完成已经彻底改变了我们对假星系的理解，将矮星系的清单扩展到了亮度，使它们变得如此微弱，以至于它们模糊了星系和星形群之间的传统区别。这些观察结果强调了在小尺度上对LCDM面临的潜在致命挑战，包括在矮星系中心缺乏暗物质的“尖”。与预测的低质量暗物质光环的巨大丰富性相比，低质量星系的稀缺原则上能够托管它们。以及银河系和仙女座星系的矮人卫星的运动学和空间排列中的奇特。所有这些问题都是积极调查的主题，尤其是因为对LCDM范式的合理（但激进）修改（例如“温暖”或“自我相互作用”的暗物质）提供了有吸引力的替代方法。因此，与LCDM预测的数据对抗已知的最小星系的对抗具有验证或质疑与用于调整其主要参数的量表上已建立的范式的承诺。旨在评估自然最小的外乳术对象的宇宙学意义的一致努力似乎已经成熟了。我建议使用各种观察和理论工具来研究此主题，从详细的N体型模拟暗物质光环的形成到对发光矮星系的形成的气体动力模拟，直接直接观察到的观察性工作，旨在调查当地宇宙中最微弱的星系，并了解它们对我们的银河系的影响。