标题： 关于 ΛCDM 中的两个小尺度问题的持续性 显示英文标题

标题： On the persistence of two small-scale problems in ΛCDM

摘要： 我们研究了在星系尺度上包含重子物理能否克服标准宇宙学模型的两个长期存在的问题：（i）本星系群星系周围的卫星平面问题；（ii）“太大而无法失败”问题。 通过比较耗散和非耗散模拟，我们发现没有迹象表明加入重子物理会导致类似银河系系统的卫星分布更加扁平化。 与此相反的最新主张被证明部分来源于一个非标准的扁平化程度度量方法，该方法忽略了卫星的径向位置。 如果考虑卫星星系的完整三维位置，则我们分析的所有模拟均未能重现银河系卫星系统的观测到的扁平化程度以及动力学一致性程度。 我们的结果与重子物理对数百千秒差距尺度上的卫星系统结构影响甚微的预期一致。 同时，声称通过加入重子物理可以解决“太大而无法失败”问题的说法也被证明存在问题。 显示英文摘要

摘要： We investigate the degree to which the inclusion of baryonic physics can overcome two long-standing problems of the standard cosmological model on galaxy scales: (i) the problem of satellite planes around Local Group galaxies, and (ii) the "too big to fail" problem. By comparing dissipational and dissipationless simulations, we find no indication that the addition of baryonic physics results in more flattened satellite distributions around Milky-Way-like systems. Recent claims to the contrary are shown to derive in part from a non-standard metric for the degree of flattening, which ignores the satellites' radial positions. If the full 3D positions of the satellite galaxies are considered, none of the simulations we analyse reproduce the observed flattening nor the observed degree of kinematic coherence of the Milky Way satellite system. Our results are consistent with the expectation that baryonic physics should have little or no influence on the structure of satellite systems on scales of hundreds of kiloparsecs. Claims that the "too big to fail" problem can be resolved by the addition of baryonic physics are also shown to be problematic.