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arXiv 2009.11547astro-ph.COhep-th
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全球21厘米信号对原始黑洞和曲率扰动的约束

Constraints on primordial black holes and curvature perturbations from the global 21cm signal

Yupeng Yang

备注：
10pages, 4 figure, comments welcome
发表信息：
Phys. Rev. D 102, 083538 (2020)
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摘要：

最近的EDGES全球21厘米信号和LIGO/VIGO的引力波观测重新引起了人们对PBH的兴趣。与以往的工作不同，我们研究了PBH对质量范围为$6\times 10^{13} {\rm g} \lesssim M_{\rm PBH}\lesssim 3\times 10^{14} \rm g$的IGM演化的影响。由于这些PBH的寿命小于宇宙的当前年龄，它们在今天已经蒸发了。由于霍金辐射的存在，PBH对IGM的加热效应可以抑制全球21 cm信号的吸收幅度。在这项工作中，通过要求全球21厘米信号在$10\lesssim z \lesssim 30$的红移范围内的差分亮温，例如，$δT_{b} \lesssim -100~\rm mK$，我们得到的PBH的初始质量分数的上限。我们发现最强的上限是$β_{\rm PBH} \sim 2\times 10^{-30}$。由于PBH的形成与原始曲率扰动有关，通过对PBH初始质量分数的限制，我们得到了对应于本文所考虑质量范围的尺度范围$8.0\times 10^{15}\lesssim k \lesssim 1.8\times 10^{16}~\rm Mpc^{-1}$的原始曲率扰动功率谱的上限.我们发现最强的上限是$\mathcal P_{\mathcal R}(k) \sim 0.0046$。通过与前人工作的比较，我们发现，对于本文所研究的质量范围（或尺度范围），21 cm信号或21 cm功率谱应该给出PBH初始质量分数和原初曲率扰动功率谱的最强上限。

英文摘要：

The recent observations of the global 21cm signal by EDGES and gravitational waves by LIGO/VIGO have revived interest in PBHs. Different from previous works, we investigate the influence of PBHs on the evolution of the IGM for the mass range $6\times 10^{13} {\rm g} \lesssim M_{\rm PBH}\lesssim 3\times 10^{14} \rm g$. Since the lifetime of these PBHs is smaller than the present age of the Universe, they have evaporated by the present day. Due to Hawking radiation, the heating effects of PBHs on the IGM can suppress the absorption amplitude of the global 21cm signal. In this work, by requiring that the differential brightness temperature of the global 21cm signals in the redshift range of $10\lesssim z \lesssim 30$, e.g., $δT_{b} \lesssim -100~\rm mK$, we obtain upper limits on the initial mass fraction of PBHs. We find that the strongest upper limit is $β_{\rm PBH} \sim 2\times 10^{-30}$. Since the formation of PBHs is related to primordial curvature perturbations, by using the constraints on the initial mass fraction of PBHs we obtain the upper limits on the power spectrum of primordial curvature perturbations for the scale range $8.0\times 10^{15}\lesssim k \lesssim 1.8\times 10^{16}~\rm Mpc^{-1}$, corresponding to the mass range considered here. We find that the strongest upper limit is $\mathcal P_{\mathcal R}(k) \sim 0.0046$. By comparing with previous works, we find that for the mass range (or the scale range) investigated in this work the global 21cm signals or the 21cm power spectrum should give the strongest upper limits on the initial mass fraction of PBHs and on the power spectrum of primordial curvature perturbations.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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