arXiv 2007.064172020-07astro-ph.CO

预复合时期的能量注入和EDGES检测

Energy injection in pre-recombination era and EDGES detection

Nirmalya Brahma, Shiv Sethi, Shivnag Sista

备注：: 22 pages, 3 figures; V3: references added
发表信息：: JCAP12(2020)034
DOI：: 10.1088/1475-7516/2020/12/034

摘要：

我们研究了解释最近的EDGES检测的能量注入在预复合时代的可能性。我们的目的是表明，这种能量注入的剩余部分可以在频率$x_e \equiv hν/(kT) \simeq 10^{-3}$处产生能量密度的增加，这是解释EDGES结果所需要的。我们考虑两种能量注入模型：注入红移固定的高斯分布和非相对论粒子的辐射衰变。我们表明，能量注入应该发生在红移范围内的$z\lesssim 4 \times 10^3$，以防止自由的过程热化注入的能量。注入的能量应接近$x_e \simeq 10^{-3}$处CMB强度的200- 1000倍，以获得所需的残留物。大部分注入的能量被热化，因此使CMB光谱失真。我们计算两种模型的CMB谱失真，并表明CMB能量密度的分数变化，$Δρ_{\rm \scriptscriptstyle CMB}/ρ_{\rm \scriptscriptstyle CMB} \simeq 10^{-6}$，这可能是检测与拟议的实验PIXIE。我们还概述了我们提出的方案的CMB各向异性的影响。

英文摘要：

We study the possibility of explaining the recent EDGES detection by an energy injection in the pre-recombination era. Our aim is to show that the residue of this energy injection could give the resultant increase in the energy density at frequencies $x_e \equiv hν/(kT) \simeq 10^{-3}$, which is needed to explain the EDGES result. We consider two models of energy injection: Gaussian profile with a fixed redshift of injection and radiative decay of a non-relativistic particle. We show that the energy injection should occur in the redshift range $z\lesssim 4 \times 10^3$ to prevent free-free processes from thermalizing the injected energy. The injected energy should be nearly 200--1000 times the CMB intensity at $x_e \simeq 10^{-3}$ to obtain the requisite residue. A large fraction of the injected energy gets thermalized and therefore distorts the CMB spectrum. We compute CMB spectral distortion for both the models and show that the fractional change in CMB energy density, $Δρ_{\rm \scriptscriptstyle CMB}/ρ_{\rm \scriptscriptstyle CMB} \simeq 10^{-6}$, which might be detectable with the proposed experiment PIXIE. We also outline the implication of our proposed scenario for CMB anisotropies.

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摘要：

英文摘要：

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