Title: A Universal Model for Evolution of Dark Matter Halos

Speaker: Professor Donghai Zhao (Shanghai Astronomical Observatory, Chinese Academy of Sciences)

Time: 13:30pm, June 02, 2021

Location: 5-516, PMO Xianlin Campus

Abstract: Dark matter halos are the elementary units of the large-scale structure of the Universe and host galaxy formation. However, their formation and evolution are highly nonlinear gravitational processes, and the analytical theory of structure formation and evolution can only give an approximate image, while the numerical simulation studies have the defects of limited applicability, non-transferability and physical ambiguity, and suffer from numerical effects. By presenting the results of numerical simulations into the parameter space adopted by the analytical theory, a new approach was proposed by Donghai Zhao et al. in 2009, to obtain a universal model for halo mass growth and its internal structure evolution. I will show in this report this model applies precisely to any dark halo mass, to any period in the history of the Universe, to a wide variety of cosmological models and to not only cold but also warm and hot dark matter models, and thus are unquestionably applicable to our real universe. Following this approach, our research group has recently proposed a unified model of dark matter halo merger rate and a unified model of dark matter halo merger orbit, both of which are again accurate and universal, while physically clear. I’ll show also our new results on the anisotropy of velocity dispersion of smooth matter inside dark matter halos.