暖热星际介质的高分辨率网格基模拟
High Resolution Grid-based Simulations of the Warm-Hot Intergalactic Medium
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中文总结 AI 辅助
本研究利用GPU优化网格代码Kratos进行高分辨率宇宙学模拟，发现WHIM重子比例约23.4%，低于先前估计，并证明空间分辨率通过辐射冷却显著影响该比例，为未来X射线任务提供预测。
中文摘要 AI 辅助
我们使用GPU优化的网格基流体动力学代码Kratos，对暖热星际介质（WHIM）进行了高分辨率宇宙学流体动力学模拟。在(100 h^-1 Mpc)^3的共动体积内采用均匀的4096^3网格，我们实现了约24.5 h^-1 kpc的空间分辨率，足以解析温度T ~ 10^4 K、氢数密度n_H ~ 10^-3至10^-2 cm^-3的气体的金斯尺度。该计算位列迄今进行的最大规模网格基宇宙学流体动力学模拟之一。我们发现，在z = 0时，约23.4%的宇宙重子存在于WHIM相（T = 10^5 - 10^7 K）中，显著低于早期较低分辨率模拟中发现的40-50%。通过一系列较低分辨率的模拟，我们证明空间分辨率在决定WHIM比例中起着关键作用：解析接近其金斯尺度的气体使其能够达到更高密度，在那里增强的辐射冷却将大量重子转移出WHIM温度范围。剩余的WHIM主要存在于晕附近的丝状结构和吸积激波结构中，在那里分层结构形成和持续的流体动力学吸积提供了持续的激波加热。莱曼α、O VI、O VII和O VIII发射的合成观测揭示了明显的形态和运动学特征，其中O VI追踪丝状-晕界面，而X射线谱线探测与大质量晕相关的更热气体。这些预测强调了当前和未来任务如XRISM、ATHENA和HUBS在绘制WHIM热力学和运动学方面的重要性。
英文摘要
We present high-resolution cosmological hydrodynamic simulations of the Warm-Hot Intergalactic Medium (WHIM) using the GPU-optimized grid-based hydrodynamic code Kratos. Employing a uniform 4096^3 grid in a (100 h^-1 Mpc)^3 comoving volume, we achieve a spatial resolution of ~24.5 h^-1 kpc, sufficient to resolve the Jeans scale of gas at T ~ 10^4 K and n_H ~ 10^-3 to 10^-2 cm^-3. This calculation ranks among the largest grid-based cosmological hydrodynamic simulations performed to date. We find that ~23.4% of cosmic baryons reside in the WHIM phase (T = 10^5 - 10^7 K) at z = 0, significantly below the 40-50% found in earlier, lower-resolution simulations. Through a suite of lower-resolution simulations, we demonstrate that spatial resolution plays a pivotal role in determining the WHIM fraction: resolving gas near its Jeans scale allows it to reach higher densities, where enhanced radiative cooling transfers a substantial fraction of baryons out of the WHIM temperature range. The remaining WHIM resides predominantly in filaments and accretion-shock structures in the vicinity of halos, where hierarchical structure formation and ongoing hydrodynamic accretion provide continued shock heating. Synthetic observations of Lyman-alpha, O VI, O VII, and O VIII emission reveal distinct morphological and kinematic signatures, with O VI tracing filament-halo interfaces and the X-ray lines probing hotter gas associated with massive halos. These predictions underscore the importance of current and future missions such as XRISM, ATHENA, and HUBS for mapping WHIM thermodynamics and kinematics.
发表机构
- The Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学）
- Department of Astronomy, School of Physics, Peking University（北京大学）
- Institute for Advanced Study in Physics, Zhejiang University（浙江大学）
- Institute of Astronomy, School of Physics, Zhejiang University（浙江大学）
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