Cannibalism hinders growth: Cannibal Dark Matter and the S8 tension
Cannibalism hinders growth: Cannibal Dark Matter and the S8 tension
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DOI：
10.1088/1475-7516/2020/12/016
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发表时间：
2020-08
影响因子：
6.4
通讯作者：
S. Heimersheim;Nils Schöneberg;D. C. Hooper;J. Lesgourgues
中科院分区：
文献类型：
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作者：
S. Heimersheim;Nils Schöneberg;D. C. Hooper;J. Lesgourgues
许多暗物质的模型被提出来试图缓解弱透镜和CMB实验之间的S8张力。其中一个令人兴奋的可能性是同类相食的暗物质（CanDM），它具有不断变化的相互作用，使其能够在非相对论性状态下保持温暖。在这里，我们调查的宇宙学意义的CanDM和它如何影响CMB各向异性和物质的功率谱，通过实施模型内的线性爱因斯坦-玻尔兹曼求解器。我们发现，CanDM抑制小尺度物质功率谱的方式非常类似于光暖暗物质或热暗物质。然而，与这些模型不同的是，在CanDM模型仍然与CMB约束兼容的情况下，可能会发生抑制。我们把强烈的约束的相互作用强度的CanDM作为其丰度的函数恒定和温度依赖的热平均截面。我们发现，CanDM模型可以很容易地解决S8张力（但对哈勃张力没有影响）。实际上，它可以容纳0.76量级的S8值，同时与CMB+BAO数据兼容。然而，只要S8张力保持适度，考虑到额外自由参数的数量，总体χ2改善相对较小，并且CanDM模型不是显著优选的。
Many models of dark matter have been proposed in attempt to ease the S8 tension between weak lensing and CMB experiments. One such exciting possibility is cannibalistic dark matter (CanDM), which has exothermal number-changing interactions allowing it to stay warm far into its non-relativistic regime. Here we investigate the cosmological implications of CanDM and how it impacts CMB anisotropies and the matter power spectrum, by implementing the model within a linear Einstein-Boltzmann solver. We show that CanDM suppresses the small scale matter power spectrum in a way very similar to light Warm Dark Matter or Hot Dark Matter. However, unlike in those models, the suppression may happen while the CanDM model still remains compatible with CMB constraints. We put strong constraints on the interaction strength of CanDM as a function of its abundance for both constant and temperature-dependent thermally-averaged cross sections. We find that the CanDM model can easily solve the S8 tension (but has no impact on the Hubble tension). Indeed, it can accommodate values of S8 of the order of 0.76 while being compatible with CMB+BAO data. However, as long as the S8 tension remains moderate, the overall χ2 improvement is relatively small given the number of extra free parameters, and the CanDM model is not significantly preferred.