发表机构
European Southern Observatory; Excellence Cluster ORIGINS; Ludwig-Maximilians-Universität München; University of São Paulo; INAF – Osservatorio Astronomico di Trieste; IFPU – Institute for Fundamental Physics of the Universe; INFN, Sezione di Trieste; ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing; Max-Planck-Institut für Astrophysik（欧洲南方天文台; 卓越集群ORIGINS; 慕尼黑大学; 圣保罗大学; 意大利国家天体物理研究所的里雅斯特天文台; 宇宙基础物理研究所; 意大利国家核物理研究所的里雅斯特分部; 高性能计算、大数据和量子计算国家研究中心; 马克斯·普朗克天体物理学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用Magneticum流体动力学模拟测试X射线选系统与晕组装的相关性，测量固定晕质量下X射线光度和气体分数选的系统聚类，发现X射线亮晕聚类更强，气体分数依赖性更强，形成时间也捕捉到很多信号。
AI 中文摘要
星系团和星系群追踪大尺度物质分布，其聚类通常主要解释为晕质量的函数。然而，在固定质量下，它们的重子性质保留了有关晕增长、气体吸积和反馈的信息。X射线光度和气体分数的固有散射表明，X射线选系统可能不是晕群体的随机子集。如果这些可观测量与晕组装相关，它们可能追踪晕偏差的二次变化。我们使用Magneticum流体动力学模拟对此进行测试，测量在固定晕质量下由X射线光度和气体分数选择的系统的聚类。我们通过按X射线光度百分位数对晕进行排名来构建质量匹配的子样本，并从晕-物质交叉功率谱中得出线性晕-物质偏差。在固定质量下，X射线亮晕比X射线暗晕聚类更强。对于第84-16百分位数分割，我们发现$\Delta b_{\rm lin}=0.17\pm0.03$，相对于X射线暗样本增强约17%。第67-33分割给出一致信号，$\Delta b_{\rm lin}=0.12\pm0.02$，增强约12%。这种效应在星系群尺度上最强，对于星系团大小的晕可以忽略不计。气体分数显示出更强的聚类依赖性，对于两个百分位数分割，相对增强约39%和约26%。这个信号从$z\simeq2$就存在，而X射线光度只有在$z\simeq0.3$时才变得显著，一旦气体热力学状态与重子保留更紧密耦合。通过质量和形成时间匹配晕将大尺度偏差差异降低到$2\sigma$以下，表明形成时间捕捉了大部分信号。这些结果表明，在Magneticum中，X射线光度追踪了晕组装偏差超出质量的重子表现。
英文摘要
Galaxy groups and clusters trace the large-scale matter distribution, with their clustering usually interpreted mainly as a function of halo mass. Yet, at fixed mass, their baryonic properties retain information about halo growth, gas accretion, and feedback. The intrinsic scatter in X-ray luminosity and gas fraction suggests that X-ray-selected systems may not be a random subset of the halo population. If these observables correlate with halo assembly, they may trace secondary variations in halo bias. We test this using the Magneticum hydrodynamical simulation, measuring the clustering of systems selected by X-ray luminosity and gas fraction at fixed halo mass. We construct mass-matched subsamples by ranking halos in percentiles of X-ray luminosity and derive the linear halo-matter bias from the halo-matter cross-power spectrum. X-ray-bright halos are more strongly clustered than X-ray-faint halos at fixed mass. For the 84th-16th percentile split, we find $Δb_{\rm lin}=0.17\pm0.03$, corresponding to a $\sim17\%$ enhancement relative to the X-ray-faint sample. A 67th-33rd split gives a consistent signal, with $Δb_{\rm lin}=0.12\pm0.02$ and a $\sim12\%$ enhancement. The effect is strongest at group scales and negligible for cluster-size halos. Gas fraction shows an even stronger clustering dependence, with relative enhancements of $\sim39\%$ and $\sim26\%$ for the two percentile splits. This signal is present from $z\simeq2$, whereas X-ray luminosity becomes significant only at $z\simeq0.3$, once the gas thermodynamic state is more closely coupled to baryon retention. Matching halos by both mass and formation time reduces the large-scale bias difference to below $2σ$, indicating that formation time captures much of the signal. These results show that, in Magneticum, X-ray luminosity traces a baryonic manifestation of halo assembly bias beyond mass.
CommentsAccepted for publication in Astronomy & Astrophysics. 11 pages, 6 figures. Abstract adapted to ArXiv
Journal refA&A, 713, A50 (2026)
DOI：10.1051/0004-6361/202660015
