Galaxy clusters, employed by Zwicky to demonstrate the existence of dark matter (DM), pose new stringent tests. First, the possibility is considered that merging clusters demonstrate that DM is self-interacting with cross-section [Formula: see text] 2[Formula: see text]cm2/gr. In that case, MACHOs, primordial black holes (PBHs) and light axions that build MACHOs are ruled out as cluster DM, while GeV and TeV WIMPs and keV sterile neutrinos are challenged. Next, recent strong lensing and X-ray gas data of the quite relaxed and quite spherical cluster A1835 are analyzed. These lensing data involve a covariance matrix of which the small eigenvalues have to be regularized. This is achieved with a new, general, parameter-free method: binning with respect to a model fit, and accounting for intra-bin fluctuations. This method allows to test the cases of DM with Maxwell–Boltzmann, Bose–Einstein and Fermi–Dirac (FD) distribution, next to Navarro–Frenck–White profiles. Fits to all these profiles are formally rejected at over [Formula: see text], except in the fermionic situation. The interpretation in terms of pseudo-Dirac neutrinos with mass of [Formula: see text][Formula: see text]eV/[Formula: see text] is consistent with results on the cluster A1689, with the DM fractions from WMAP, Planck and DES, and with the non-detection of neutrinoless double [Formula: see text]-decay. The predicted mass will be tested in the KATRIN and PTOLEMY experiments.

中文翻译：

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对暗物质候选者进行集群测试

Zwicky 用来证明暗物质 (DM) 存在的星系团提出了新的严格测试。首先，考虑合并簇的可能性表明DM与横截面自相互作用[公式：见文本] 2 [公式：见文本]cm2/克。在这种情况下，构建 MACHO 的 MACHO、原始黑洞 (PBH) 和轻轴子被排除在集群 DM 之外，而 GeV 和 TeV WIMP 以及 keV 无菌中微子则受到挑战。接下来，分析了相当松弛且相当球形的星团A1835最近的强透镜和X射线气体数据。这些透镜数据涉及一个协方差矩阵，其中的小特征值必须进行正则化。这是通过一种新的、通用的、无参数的方法实现的：根据模型拟合进行分箱，并考虑箱内波动。该方法允许测试具有 Maxwell-Boltzmann、Bose-Einstein 和 Fermi-Dirac (FD) 分布的 DM 案例，旁边是 Navarro-Frenck-White 轮廓。除了在费米子情况下，所有这些配置文件的拟合都在 [公式：参见文本] 处被正式拒绝。质量为 [公式：见文本][公式：见文本]eV/[公式：见文本] 的伪狄拉克中微子的解释与 A1689 星团的结果一致，与 WMAP、Planck 和DES，并与无中微子双[公式：见正文]-衰变的非检测。预测的质量将在 KATRIN 和 PTOLEMY 实验中进行测试。