论文标题
用宇宙微波背景和弱透镜剪切观测来约束暗物质腐烂
Constraining dark matter decays with cosmic microwave background and weak lensing shear observations
论文作者
论文摘要
从低红移和高红移的观察结果来看，众所周知，大部分暗物质（DM）必须稳定或至少长寿。但是，一小部分DM不稳定，或者所有DM在半衰期时间（$τ$）衰减的可能性明显比宇宙年龄更长。一体衰减的暗物质（DDM）由$λ$ CDM型号的最小扩展组成。它导致对宇宙生长历史的修改以及对小规模聚类信号的抑制，从而为$ s_8 $张力带来了有趣的后果，这是观察到的弱透镜（WL）和宇宙微波背景（CMB）观察之间观察到的聚类幅度差异。在本文中，我们调查了分数或所有DM均辐射到辐射中的模型，重点是长期寿命的制度，即$τ\ gtrsim H_0^{ - 1} $（$ H_0^{ - 1} $是Hubble Time）。我们使用了来自Planck的Kilo-Degree调查（儿童）和CMB数据中的WL数据。首先，我们确认此DDM模型无法减轻$ S_8 $差异。然后，我们证明DM衰减的最严格功率不是来自非线性WL数据，而是通过集成的Sachs-Wolfe效应来自CMB。从仅CMB数据中，如果假定所有DM都不稳定，我们就会获得$τ\ geq 288 $ 〜Gyr的约束，并且我们表明，假设半寿命的时间比（或更短的时间比）一个笨拙的时间可比（或更短的时间），则允许$ f = 0.07 $的最大分数。来自Kids-1000 WL数据的约束明显较弱，$τ\ geq 60 $ 〜Gyr和$ f <0.34 $。将CMB和WL数据组合起来不会产生比CMB的更严格的约束，除了短期寿命时间，最大允许的分数变为$ f = 0.03 $。所有限制均以95％的置信度提供。
From observations at low and high redshifts, it is well known that the bulk of dark matter (DM) has to be stable or at least very long-lived. However, the possibility that a small fraction of DM is unstable or that all DM decays with a half-life time ($τ$) significantly longer than the age of the Universe is not ruled out. One-body decaying dark matter (DDM) consists of a minimal extension to the $Λ$CDM model. It causes a modification of the cosmic growth history as well as a suppression of the small-scale clustering signal, providing interesting consequences regarding the $S_8$ tension, which is the observed difference in the clustering amplitude between weak-lensing (WL) and cosmic microwave background (CMB) observations. In this paper, we investigate models in which a fraction or all DM decays into radiation, focusing on the long-lived regime, that is, $τ\gtrsim H_0^{-1}$ ( $H_0^{-1}$ being the Hubble time). We used WL data from the Kilo-Degree Survey (KiDS) and CMB data from Planck. First, we confirm that this DDM model cannot alleviate the $S_8$ difference. We then show that the most constraining power for DM decay does not come from the nonlinear WL data, but from CMB via the integrated Sachs-Wolfe effect. From the CMB data alone, we obtain constraints of $τ\geq 288$~Gyr if all DM is assumed to be unstable, and we show that a maximum fraction of $f=0.07$ is allowed to decay assuming the half-life time to be comparable to (or shorter than) one Hubble time. The constraints from the KiDS-1000 WL data are significantly weaker, $τ\geq 60$~Gyr and $f<0.34$. Combining the CMB and WL data does not yield tighter constraints than the CMB alone, except for short half-life times, for which the maximum allowed fraction becomes $f=0.03$. All limits are provided at the 95% confidence level.
