arXiv 2205.136282022-05astro-ph.COhep-ph

衰变的暖暗物质再探

Decaying warm dark matter revisited

Emil Brinch Holm, Thomas Tram, Steen Hannestad

备注：: 41 pages (main text 25 pages), 16 figures; v2: minor corrections, submitted to JCAP

摘要：

衰变的暗物质模型提供了一种物理上激发的方式，在物质和辐射扇区之间引导能量。原则上，这可能会影响哈勃常数的预测值，以适应CMB推断与当地测量结果之间的差异。在这里，我们重新审视了温暖的暗物质非相对论性地衰变为不可见辐射的模型。特别是，我们重新推导的背景和微扰方程从一个衰变中微子模型，并描述了一个新的，计算效率高的方法计算的衰变产物微扰大多极。我们进行MCMC分析，以约束所有三个模型参数，第一次包括衰变物种的质量，并评估该模型的能力，以减轻哈勃和$σ_8$紧张局势，后者是CMB和弱引力透镜之间的差异约束的幅度上的$8 h^{-1}$ Mpc $^{-1}$规模的物质波动。我们发现，该模型降低了$H_0$张力从$\sim 4 σ$到$\sim 3 σ$，既不增加也不减少$S_8 \equiv σ_8 (Ω_m/0.3)^{0.5}$张力，最终仅显示出相对于$Λ$ CDM的轻微改善。然而，模型的具体参数的值有利于数据被发现是很好的相对论性衰变的逆过程是重要的，呈现一个结论性的评估的衰变温暖的暗物质模型开放未来的工作范围内。

英文摘要：

Decaying dark matter models provide a physically motivated way of channeling energy between the matter and radiation sectors. In principle, this could affect the predicted value of the Hubble constant in such a way as to accommodate the discrepancies between CMB inferences and local measurements of the same. Here, we revisit the model of warm dark matter decaying non-relativistically to invisible radiation. In particular, we rederive the background and perturbation equations starting from a decaying neutrino model and describe a new, computationally efficient method of computing the decay product perturbations up to large multipoles. We conduct MCMC analyses to constrain all three model parameters, for the first time including the mass of the decaying species, and assess the ability of the model to alleviate the Hubble and $σ_8$ tensions, the latter being the discrepancy between the CMB and weak gravitational lensing constraints on the amplitude of matter fluctuations on an $8 h^{-1}$ Mpc$^{-1}$ scale. We find that the model reduces the $H_0$ tension from $\sim 4 σ$ to $\sim 3 σ$ and neither alleviates nor worsens the $S_8 \equiv σ_8 (Ω_m/0.3)^{0.5}$ tension, ultimately showing only mild improvements with respect to $Λ$CDM. However, the values of the model-specific parameters favoured by data is found to be well within the regime of relativistic decays where inverse processes are important, rendering a conclusive evaluation of the decaying warm dark matter model open to future work.

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