Sterile neutrinos as dark matter.
Sterile neutrinos as dark matter.
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DOI：
10.1103/physrevlett.72.17
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发表时间：
1993-03
影响因子：
8.6
通讯作者：
S. Dodelson;L. Widrow
中科院分区：
文献类型：
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作者：
S. Dodelson;L. Widrow
最简单的模型，可以容纳一个可行的非重子暗物质的候选者是标准的电弱理论，加上右手或不育中微子。这个模型已经在热暗物质场景的背景下被广泛研究。我们重新审视了这个模型，发现热、暖、冷的暗物质都是可能的。我们专注于无菌中微子是暗物质的情况。由于它们唯一的直接耦合是与左手或活动中微子，最有效的产生机制是通过中微子振荡。如果中微子的产生速率总是小于膨胀速率，那么这些中微子将永远不会处于热平衡状态。然而，它们仍然可能在宇宙的动力学中发挥重要作用，并可能提供闭合所需的缺失质量。我们考虑单代中微子场（[nu][sub L]，[nu][sub R]），其Dirac质量为[mu]，仅右手分量为Majorana质量M。对于M [much gt] [mu]，我们证明了无菌中微子的数密度与[mu][sup 2]/M成正比，因此今天的能量密度与M无关。然而，M在确定宇宙的大尺度结构方面至关重要。更多»特别是，M [约等于] 0.1- 1.0关键导致温暖的暗物质和结构形成场景，可能比标准的热和冷暗物质场景都有一些优势。«少
The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ([nu][sub L], [nu][sub R]) with a Dirac mass, [mu], and a Majorana mass for the right-handed components only, M. For M [much gt] [mu] we show that the number density of sterile neutrinos is proportional to [mu][sup 2]/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe.more » In particular, M [approx equal] 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.« less