The effects of relativistic hidden sector particles on the matter power spectrum
The effects of relativistic hidden sector particles on the matter power spectrum
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DOI：
10.1088/1475-7516/2023/01/004
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发表时间：
2022-09
影响因子：
6.4
通讯作者：
Himanish Ganjoo;A. Erickcek;Weikang Lin;K. Mack
中科院分区：
文献类型：
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作者：
Himanish Ganjoo;A. Erickcek;Weikang Lin;K. Mack
如果暗物质存在于与标准模型耦合最小的隐藏扇区中，那么隐藏扇区中的另一种粒子可能暂时支配早期宇宙的能量密度，从而导致早期物质主导时代（EMDE）。在EMDE期间，物质扰动比在辐射主导时期增长得更快，这导致微晕的形成比在标准宇宙学情景中形成的要早得多。这些微光晕增强了暗物质湮灭信号，但这种增强对物质功率谱的小范围截止非常敏感。如果暗物质足够冷，这个临界值是由主导隐藏区域的粒子的相对论压力设定的。我们确定了这种情况下暗物质密度扰动的演化，获得了EMDE结束时的功率谱。我们分析了显性隐藏扇形粒子的相对论性压力对扰动的抑制作用，并用该粒子的性质表示了物质功率谱最大的截止尺度和峰值尺度。我们还提供了传递函数，将由主要隐藏扇区粒子的压力产生的小范围截止的物质功率谱与由冷隐藏扇区产生的物质功率谱联系起来。这些传递函数有助于在具有初始热隐藏扇区的EMDE场景中快速计算准确的物质功率谱，并使我们能够确定哪些模型显著增强了微晕丰度。
If dark matter resides in a hidden sector minimally coupled to the Standard Model, another particle within the hidden sector might dominate the energy density of the early universe temporarily, causing an early matter-dominated era (EMDE). During an EMDE, matter perturbations grow more rapidly than they would in a period of radiation domination, which leads to the formation of microhalos much earlier than they would form in standard cosmological scenarios. These microhalos boost the dark matter annihilation signal, but this boost is highly sensitive to the small-scale cut-off in the matter power spectrum. If the dark matter is sufficiently cold, this cut-off is set by the relativistic pressure of the particle that dominates the hidden sector. We determine the evolution of dark matter density perturbations in this scenario, obtaining the power spectrum at the end of the EMDE. We analyze the suppression of perturbations due to the relativistic pressure of the dominant hidden sector particle and express the cut-off scale and peak scale for which the matter power spectrum is maximized in terms of the properties of this particle. We also supply transfer functions to relate the matter power spectrum with a small-scale cut-off resulting from the pressure of the dominant hidden sector particle to the matter power spectrum that results from a cold hidden sector. These transfer functions facilitate the quick computation of accurate matter power spectra in EMDE scenarios with initially hot hidden sectors and allow us to identify which models significantly enhance the microhalo abundance.