反弹星系对星系成团偏差的影响
The Impact of Splashback Galaxies on Galaxy Assembly Bias
AI总结：
本研究借助Millennium模拟和TNG300模拟，探究反弹星系对星系并合偏差的影响，明确反弹星系的特征及其对星系成团性信号的作用，为星系-晕连接建模提供参考。
AI中文摘要：
星系的成团性受其 underlying 暗物质晕的并合历史影响，这一被称为星系并合偏差的复杂现象已被广泛研究，但其确切物理起源仍不明确。反弹晕（通常是穿越过更大邻近晕的低质量晕）被认为与晕并合偏差相关。本研究采用应用于Millennium模拟的半解析星系形成模型，明确探究反弹星系在星系并合偏差中的作用。我们将反弹星系定义为现今曾是更大质量宿主卫星的中心星系，并构建了按恒星质量筛选的星系样本，分别移除反弹星系或将其重新归类为原宿主晕的卫星。研究发现，反弹星系倾向于位于低质量、高集中度的晕及致密环境中，且具有相对较高的恒星质量-晕质量比；它们在很大程度上导致了高集中度晕和致密环境晕的占据度变化的低质量尾端。最后，在计算并合偏差对星系成团性的影响时，我们发现移除反弹星系会显著降低信号，重新分配它们对信号振幅影响较小，但会改变转变尺度。我们还采用流体动力学模拟TNG300重复分析，确认了结果的稳健性。本研究结果为并合偏差提供了新见解，对星系-晕连接的建模具有潜在意义。
英文摘要：
The clustering of galaxies is affected by the assembly history of their underlying dark matter halos. This complex phenomenon, known as galaxy assembly bias, has been extensively studied, but the exact physical origin remains unclear. Splashback halos, typically low-mass halos that have traversed larger neighboring halos, have been suggested to be associated with halo assembly bias. Using a semi-analytic galaxy-formation model applied to the Millennium simulation, we explicitly explore the role that splasback galaxies play in galaxy assembly bias. We identify splashbacks as present-day central galaxies that were formerly satellites of a more massive host, and construct stellar-mass selected galaxy samples with the splashbacks either removed or reclassified as satellites of their former host halo. We find that splashbacks tend to reside in low-mass, highly concentrated halos and in dense environments, and that they have relatively high stellar-to-halo mass ratios. Splashbacks appear to be largely responsible for the low-mass tail of the occupancy variation for highly concentrated halos and for halos in dense environments. Finally, when computing the impact of assembly bias on galaxy clustering, we find that while removing the splashbacks significantly reduces the signal, reassigning them has little effect on its amplitude but shifts the transition scale. We repeat the analysis with the hydrodynamical simulation TNG300, confirming the robustness of our results. Our results provide insight into assembly bias and have potential implications for modeling the galaxy-halo connection.
