We address the 'plane of satellites problem' by studying planar configurations around two disc galaxies with no late major mergers, formed in zoom-in hydro-simulations. Due to the current lack of good quality kinematic data for M31 satellites, we use only positional information. So far, positional analyses of simulations are unable to find planes as thin and populated as the observed ones. Moreover, they miss systematicity and detail in the plane-searching techniques, as well as in the study of the properties and quality of planes, both in simulations or real data. To fill this gap, i) we extend the 4-galaxy-normal density plot method (Pawlowski et al. 2013) in a way designed to efficiently identify the best quality planes (i.e., thin and populated) without imposing extra constraints on their properties, and ii), we apply it for the first time to simulations. Using zoom-in simulations allows us to mimic MW/M31-like systems regarding the number of satellites involved as well as the galactic disc mass and morphology, in view of possible disc effects. At all timesteps analyzed in both simulations we find satellite planar configurations that are compatible, along given time intervals, with all the spatial characteristics of observed planes identified using the same methodology. However, the fraction of co-orbiting satellites within them is in general low, suggesting time-varying satellite membership. We conclude that high-quality positional planes of satellites are not infrequent in LCDM-formed disc galaxies with a quiet assembly history. Detecting kinematically-coherent, time-persistent planes demands considering the full six-dimensional phase-space information of satellites.

中文翻译：

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模拟盘状星系周围的卫星平面。I. 从位置信息中寻找高质量平面配置及其与 MW/M31 数据的比较

我们通过研究两个盘状星系周围的平面配置来解决“卫星平面问题”，这些星系在放大的水力模拟中形成，没有晚期重大合并。由于目前缺乏高质量的 M31 卫星运动学数据，我们仅使用位置信息。到目前为止，模拟的位置分析无法找到与观察到的平面一样薄和密集的平面。此外，他们错过了平面搜索技术的系统性和细节，以及在模拟或真实数据中对平面特性和质量的研究。为了填补这一空白，i）我们扩展了 4-galaxy-normal 密度图方法（Pawlowski et al. 2013），其设计方式旨在有效识别最佳质量平面（即薄且填充的平面），而不对其属性施加额外的限制, 和 ii), 我们首次将其应用于模拟。鉴于可能的盘效应，使用放大模拟使我们能够模拟 MW/M31 类系统，涉及卫星数量以及银盘质量和形态。在两个模拟中分析的所有时间步长中，我们发现卫星平面配置在给定的时间间隔内与使用相同方法识别的观测平面的所有空间特征兼容。然而，其中的共轨卫星比例普遍较低，表明卫星成员随时间变化。我们得出的结论是，卫星的高质量定位平面在 LCDM 形成的盘状星系中并不少见，其组装历史很安静。检测运动相干，