SISSA, Via Bonomea 265, 34136 Trieste, Italy.
INFN, Sez. di Trieste, via Valerio 2, 34127 Trieste, Italy.
Phys Rev Lett. 2019 Aug 16;123(7):071102. doi: 10.1103/PhysRevLett.123.071102.
The renewed interest in the possibility that primordial black holes (PBHs) may constitute a significant part of dark matter has provided motivation for revisiting old observational constraints, as well as developing new ones. We present new limits on the PBH abundance, from a comprehensive analysis of high-resolution high-redshift Lyman-α forest data. Poisson fluctuations in the PBH number density induce a small-scale power enhancement which departs from the standard cold dark matter prediction. Using a grid of hydrodynamic simulations exploring different values of astrophysical parameters, we obtain a marginalized upper limit on the PBH mass of f_{PBH}M_{PBH}∼60M_{⊙} at 2σ, when a Gaussian prior on the reionization redshift is imposed, preventing its posterior distribution from peaking on very high values, which are disfavored by the most recent estimates obtained both through cosmic microwave background and intergalactic medium observations. Such a bound weakens to f_{PBH}M_{PBH}∼170M_{⊙} when a conservative flat prior is instead assumed. Both limits significantly improve on previous constraints from the same physical observable. We also extend our predictions to nonmonochromatic PBH mass distributions, ruling out large regions of the parameter space for some of the most viable PBH extended mass functions.
人们重新燃起了对原始黑洞 (PBH) 可能构成暗物质重要组成部分的可能性的兴趣，这促使人们重新审视旧的观测限制，并开发新的限制。我们通过对高分辨率高红移 Lyα 森林数据的全面分析，提出了 PBH 丰度的新限制。PBH 密度的泊松涨落会导致小尺度功率增强，从而偏离标准冷暗物质预测。我们使用一组探索不同天体物理参数值的流体力学模拟，当对再电离红移施加高斯先验时，在 2σ 处获得了 PBH 质量的边缘化上限 f_{PBH}M_{PBH}∼60M_{⊙}，从而防止其后验分布在非常高的值上达到峰值，这些值在通过宇宙微波背景和星系际介质观测得到的最新估计中被认为是不利的。当假设更保守的 flat 先验时，这种限制会减弱到 f_{PBH}M_{PBH}∼170M_{⊙}。这两个限制都比以前基于相同物理可观测量的限制有了显著的改进。我们还将我们的预测扩展到非单色 PBH 质量分布，排除了一些最可行的 PBH 扩展质量函数的大部分参数空间。
