Magneticum模拟中大质量星系团的平均软X射线表面亮度轮廓
Average soft X-ray surface brightness profile of massive galaxy clusters in Magneticum simulations
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中文总结 AI 辅助
本研究对比观测与Magneticum模拟的数十个低红移大质量星系团平均软X射线表面亮度轮廓，发现除中心区域外二者一致性良好，模拟对外围区域的探测极具挑战性。
中文摘要 AI 辅助
大质量星系团的自相似增长表明，在进行适当的质量和红移相关重标后，它们关键热力学性质的径向轮廓应具有相同的形状。这一性质在对已充分研究的单个天体样本的 virial 半径内进行了测试，结合灵敏度和背景校正等清晰且稳健的观测特征，使得叠加观测成为可能，可将其与理论或数值模拟在大半径处得出的相同推导的种群平均预测进行对比。这种对比不仅消除了单个天体性质中不可避免的随机性影响，还能提升对星系团外围最暗区域的探测灵敏度。本研究对低红移下数十个大质量星系团的观测和模拟平均软X射线表面亮度轮廓进行了一对一对比。我们发现，SRG/eROSITA 近期测量的叠加星系团的0.3-2.3 keV表面亮度轮廓与 Magneticum 宇宙学流体动力学模拟的相应预测之间存在非常好的直接一致性，已知该模拟能重现大质量星系团的其他观测标度关系。观测与模拟轮廓在非常中心区域存在显著差异，其中AGN反馈的有效实施可能导致核心内气体过度重分布。模拟预测，在星系团 virial 半径数倍之外的区域，表面亮度轮廓会非常嘈杂，平均信号比局部径向平坦但波动强烈的发射背景低几个数量级，这意味着即使未来使用更大样本，也很难对这一成分进行恰当探测。
英文摘要
The self-similar growth of massive galaxy clusters suggests that radial profiles of their key thermodynamic properties should have identical shapes after proper mass- and redshift-dependent re-scaling. This property, tested within the virial radius on samples of well-studied individual objects, together with clear and robust observational characteristics such as sensitivity and background accounting, enables the possibility of stacking observations that can be confronted with identically-derived population-averaged predictions from theory or numerical simulations at large radii. Such a comparison not only eliminates effects of inevitable stochasticity in properties of individual objects, but also allows one to reach higher sensitivity for the faintest regions on the outskirts of the clusters. In this study, we conduct a one-to-one comparison of the observed and simulated average soft X-ray surface brightness profiles of several dozen massive galaxy clusters at low redshift. We find a very good out-of-the-box agreement between the 0.3 - 2.3 keV surface brightness profile of stacked galaxy clusters recently measured by SRG/eROSITA and the corresponding predictions from the Magneticum cosmological hydrodynamical simulations, which are known to reproduce other scaling relations observed for massive galaxy clusters. A significant difference between the observed and simulated profiles is present in the very central region, where effective implementation of the AGN feedback likely results in excessive gas redistribution within the core. The simulations predict a very noisy surface brightness profile beyond several times the virial radius of the cluster, with the mean signal being orders of magnitude lower than the local radially-flat but strongly fluctuating emission background, meaning that a proper detection of this component would be very challenging even with larger samples in the future.
