Context. In previous work, we developed a quasi-Gaussian approximation for the likelihood of correlation functions, which, in contrast to the usual Gaussian approach, incorporates fundamental mathematical constraints on correlation functions. The analytical computation of these constraints is only feasible in the case of correlation functions of one-dimensional random fields.
Aims. In this work, we aim to obtain corresponding constraints in the case of higher-dimensional random fields and test them in a more realistic context.
Methods. We develop numerical methods to compute the constraints on correlation functions which are also applicable for two- and three-dimensional fields. In order to test the accuracy of the numerically obtained constraints, we compare them to the analytical results for the one-dimensional case. Finally, we compute correlation functions from the halo catalog of the Millennium Simulation, check whether they obey the constraints, and examine the performance of the transformation used in the construction of the quasi-Gaussian likelihood.
Results. We find that our numerical methods of computing the constraints are robust and that the correlation functions measured from the Millennium Simulation obey them. Despite the fact that the measured correlation functions lie well inside the allowed region of parameter space, i.e. far away from the boundaries of the allowed volume defined by the constraints, we find strong indications that the quasi-Gaussian likelihood yields a substantially more accurate description than the Gaussian one.
Simulations of the galaxy population constrained by observations from z=3 to the present day: implications for galactic winds and the fate of their ejecta
我们应用蒙特卡罗马尔可夫链（MCMC）方法的大规模模拟的星系形成在LambdaCDM宇宙学，以探讨如何恒星的形成和反馈所观察到的星系的光度和恒星质量函数的约束。我们在Millennium和Millennium-II模拟上联合建立模型，应用快速采样技术，允许在7<log（M*/Msun）<12和z=0至z=3的范围内观测到的星系丰度同时用作MCMC分析中的约束。当仅施加z=0的约束时，我们重现了Guo et al.（2012）先前建模的结果，但没有一组参数可以同时重现所有红移下观测到的星系丰度，这反映了低质量星系形成过早的事实，因此在该模型中，在高红移下过于丰富。这些数据要求星系风喷出物再吸积的效率随红移和晕质量的变化与以前的假设完全不同，但与最近一些星系形成的流体动力学模拟相似。我们提出了一个具体的模型，其中重新纳入时标与晕质量成反比，是独立的红移。这产生了一个不断发展的星系人口，适合观测到的丰度作为恒星质量，B-和K-波段光度的函数，同时在所有的红移。它还在其他两个领域产生了显着的改善，而这些领域是以前的模型所不具备的。它导致了今天的矮星系人口更年轻，更蓝，更强烈的恒星形成和更弱的小规模集群比以前，虽然暗矮星的被动部分仍然太高。
Fast Baryonic Field Painting for Sunyaev-Zel'dovich Analyses: Transfer Function vs. Hybrid Effective Field Theory
University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Berkeley Center for Cosmological Physics（伯克利宇宙物理学中心）；Miller Institute for Basic Research in Science（米勒基础科学研究学院）；Institute for Computational Cosmology, Department of Physics, Durham University（达勒姆大学物理系计算宇宙学研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Excellence Cluster ORIGINS（ORIGINS卓越集群）
