Formation of Galaxies in Groups and Clusters

AST 98-03199 August Evrard 星系的形成是观测宇宙学的核心问题。 这个问题涉及到解决一组流体（暗物质，重子气体和恒星）的流体动力学和热力学行为耦合在一个高度非线性的方式在物理尺度的宽动态范围内。 数值模拟提供了一种解决这个问题的方法。 PI正在对与星系群和星系团形成的数值模拟相关的参数空间进行建模。 他使用了两个独立的代码：PI开发的P3 MSPH代码和Virgo联盟的Hydra代码。 该项目的科学目标是（1）模拟集群的哪些方面在数值上是稳健的？(2)什么过程决定了星系和星系团内介质中重子的相对分数？(3)一个单一的星系形成模型能否再现观测到的星系团和星系团的光学和x射线特征？ (4)星系如何在星系团环境中追踪总质量？ 这是一个分阶段的研究，（1）调查稳定性的数值参数，（2）校准响应星星形成和反馈处方，（3）探索整个光谱的集群大小的依赖性，（4）探索宇宙学模型的灵敏度。 ***

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. ***