Many models of dark matter have been proposed in attempt to ease the $S_8$ 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 $S_8$ tension (but has no impact on the Hubble tension). Indeed, it can accommodate values of $S_8$ of the order of 0.76 while being compatible with CMB+BAO data. However, as long as the $S_8$ tension remains moderate, the overall $\chi^2$ improvement is relatively small given the number of extra free parameters, and the CanDM model is not significantly preferred.

中文翻译：

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同类相食阻碍增长：食人族暗物质和 S8 紧张局势

已经提出了许多暗物质模型，试图缓解弱透镜和 CMB 实验之间的 $S_8$ 张力。一种令人兴奋的可能性是自相残杀的暗物质 (CanDM)，它具有放热数量变化的相互作用，使其能够在其非相对论状态下保持温暖。在这里，我们通过在线性爱因斯坦-玻尔兹曼求解器中实施模型来研究 CanDM 的宇宙学意义以及它如何影响 CMB 各向异性和物质功率谱。我们表明，CanDM 以一种非常类似于轻暖暗物质或热暗物质的方式抑制小尺度物质功率谱。然而，与那些模型不同的是，当 CanDM 模型仍然与 CMB 约束兼容时，可能会发生抑制。我们对 CanDM 的相互作用强度进行了严格的限制，作为其在恒定和温度相关热平均横截面的丰度的函数。我们发现 CanDM 模型可以轻松解决 $S_8$ 张力（但对哈勃张力没有影响）。事实上，它可以容纳 0.76 量级的 $S_8$ 值，同时兼容 CMB+BAO 数据。然而，只要 $S_8$ 的张力保持适度，考虑到额外的自由参数的数量，整体 $\chi^2$ 的改进相对较小，并且 CanDM 模型不是显着首选。76同时兼容CMB+BAO数据。然而，只要 $S_8$ 的张力保持适度，考虑到额外的自由参数的数量，整体 $\chi^2$ 的改进相对较小，并且 CanDM 模型不是显着首选。76同时兼容CMB+BAO数据。然而，只要 $S_8$ 的张力保持适度，考虑到额外的自由参数的数量，整体 $\chi^2$ 的改进相对较小，并且 CanDM 模型不是显着首选。