Formation of Galaxies in Groups and Clusters

星系的形成是观测宇宙学的一个核心复杂问题。该问题涉及求解一组流体（暗物质、重子气体和恒星）的流体动力学和热力学行为，这些流体在物理尺度上以高度非线性的方式在很宽的动态范围内耦合。数值模拟为解决这一问题提供了一种方法。PI正在模拟与星系群和星系团形成的数值模拟相关的参数空间。他使用了两个独立的代码：由PI开发的P3MSPH代码和Virgo联盟的Hydra代码，这两个代码都在并行机器上运行。该项目的科学目标是(1)建模集群的哪些方面在数值上是健壮的？(2)什么过程决定了星系和星系团内介质中重子的相对比例？(3)星系形成的单一模型能否再现观测到的星团和星团的光学和x射线特征？(4)星系如何追踪星系团环境中的总质量？这是一个分阶段的研究，目的是：(1)研究数值参数的稳定性；(2)校准对恒星形成和反馈处方的响应；(3)探索星团大小谱上的依赖性；(4)探索对宇宙学模型的敏感性。＊＊＊

AST 98-03199 August Evrard The formation of galaxies is a complex problem central to observational cosmology. The problem involves solving for the fluid dynamic and thermodynamic behavior of a set of fluids (dark matter, baryonic gas, and stars) coupled in a highly non-linear manner over a wide dynamic range in physical scales. Numerical simulations provide a means to address this problem. The PI is modeling the parameter space associated with numerical simulations of galaxy formation in groups and clusters. He is using two independent codes: the P3MSPH code developed by the PI, and the Virgo consortium's Hydra code These both run on parallel machines. The science objectives of the project are (1) what aspects of modeled clusters are numerically robust? (2) what processes determine the relative fractions of baryons in galaxies and the intracluster medium? (3) can a single model for galaxy formation reproduce the observed optical and x-ray characteristics of groups and clusters? (4) how do galaxies trace the total mass in clustered environments? This is a phased study to (1) investigate stability to numerical parameters, (2) to calibrate response to star formation and feedback prescriptions, (3) explore dependence across a spectrum of cluster sizes, (4) explore sensitivity to the cosmological model. ***