Reionization Constraints on the Contribution of Primordial Compact Objects to Dark Matter
Reionization Constraints on the Contribution of Primordial Compact Objects to Dark Matter
复制标题
原初致密天体对暗物质贡献的再电离约束
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
M. Miller
中科院分区：
文献类型：
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作者：
M. Miller
许多证据表明，非重子暗物质构成了临界闭合密度的约30%，但这种暗物质的组成尚不清楚。暗物质的一类候选者是在早期宇宙中形成的致密天体，典型质量为M ~ 0.1-1 M☉，与微透镜观测项目发现的天体的质量尺度相对应。这种类型的候选者包括在QCD相变时期形成的黑洞、夸克星和玻色子星。在这里，我们展示了这些物体的吸积在早期宇宙中产生了大量的电离，其光学深度为τ≈2 - 4[fCOϵ-1（M/M☉）]1/2(H0/65)-1到z ~ 1100的汤姆逊散射，其中ϵ-1是吸积效率λ≡L/c2除以0.1，fCO是致密物体中物质的比例。基于微波背景的各向异性，当前散射光学深度的上限为≈0.4。因此，如果这些物体的吸积相对有效，它们就不可能是非重子暗物质的主要组成部分。
Many lines of evidence suggest that nonbaryonic dark matter constitutes ~30% of the critical closure density, but the composition of this dark matter is unknown. One class of candidates for the dark matter is compact objects formed in the early universe, with typical masses M ~ 0.1-1 M☉, to correspond to the mass scale of objects found with microlensing observing projects. Specific candidates of this type include black holes formed at the epoch of the QCD phase transition, quark stars, and boson stars. Here we show that accretion onto these objects produces substantial ionization in the early universe, with an optical depth to Thomson scattering out to z ~ 1100 of τ ≈ 2 - 4[fCOϵ-1(M/M☉)]1/2(H0/65)-1, where ϵ-1 is the accretion efficiency ϵ ≡ L/c2 divided by 0.1, and fCO is the fraction of matter in the compact objects. The current upper limit to the scattering optical depth, based on the anisotropy of the microwave background, is ≈0.4. Therefore, if accretion onto these objects is relatively efficient, they cannot be the main component of nonbaryonic dark matter.