Title: Cosmological information from small scales

Speaker: 朱弘明

Institute:  国家天文台

Host: 于浩然

Time: 11.23 周四 14:30-16:30

Location: 物理楼552

Abstract: 

The large-scale structures of the Universe exhibit striking non-Gaussian features, often referred to as the cosmic web. The strong non-Gaussian nature of this system has traditionally limited the cosmological information that can be extracted from a large survey, known as the information saturation problem. In this talk, I will show how we can recover the lost small-scale information using the nonlinear reconstruction algorithm. We find that nonlinear reconstruction can improve the constraints on cosmological parameters significantly, nearly reaching the linear theory limit. Then I will discuss how we can exploit the local anisotropic small-scale non-Gaussian structures to reconstruct the large-scale matter distribution. This tidal reconstruction technique can help recover the 21 cm radial modes that are lost due to foreground contamination. Furthermore, I will demonstrate that tidal reconstruction can significantly enhance the constraints on local primordial non-Gaussianity and probe the primordial parity-violating signatures. These findings hold significant implications for current and future surveys such as DESI, PFS, CSST, and more.

Bio：

Hongming Zhu has been a faculty member at the National Astronomical Observatories, Chinese Academy of Sciences, since August 2023. He obtained his PhD at the University of Chinese Academy of Sciences in 2017. He was a BCCP fellow at the University of California, Berkeley from 2017 to 2020 and then a CITA fellow at the Canadian Institute for Theoretical Astrophysics from 2020 to 2023.