Title：Cosmology with massive spectroscopic surveys

Speaker：Zhao Cheng 赵成(Tsinghua University)

Time：3:00pm Jan. 18th (Thursday)

Tencent Meeting：42915400486 password: 6360

Location: Lecture Hall, 3rd floor

Report in English

Abstract：

As a result of the competition between gravity and cosmic expansion, large-scale structures (LSS) provide a unique way to tackle the mysteries of the dark Universe. Massive spectroscopic surveys are thus carried out to trace the LSS with the 3D positions of galaxies and quasars, as well as the radial distributions of neutral Hydrogen clouds. Recent spectroscopic surveys, such as SDSS and DESI, has collected millions of spectra of galaxies and quasars, and revealed an uninterrupted view of the cosmos over the last 11 billion years. This large dataset permits percent-level measurements of many standard cosmological parameters, such as the Hubble constant, matter fluctuation amplitude, and dark energy density. Meanwhile, a number of more massive spectroscopic surveys has been proposed to extend the 3D-map of the Universe to higher redshift, with unprecedented completeness and density.

In this talk, the speaker will introduce the design and strategy of the state-of-art spectroscopic surveys, and review the process of obtaining cosmological constraints from the raw data, with the focus on robust estimates of statistical and systematic errors. The speaker will also discuss the prospects of cosmological studies with future surveys, and present forecasts based on the Fisher information matrix.

CV：

Cheng Zhao (赵成) is a tenure-track assistant professor at Department of Astronomy, Tsinghua University. He received his BSc (2012) and PhD in astrophysics (2018) from Tsinghua University. Then he spent 4 years in Switzerland as a postdoctoral fellow at EPFL. He is mainly engaged in the study of large-scale structures of the Universe based on large-scale galaxy surveys and high-fidelity cosmological simulations. He has participated in a series of state-of-art large-scale spectroscopic surveys, such as the Baryon Oscillation Spectroscopic Survey (BOSS), the extended Baryon Oscillation Spectroscopic Survey (eBOSS), and the Dark Energy Spectroscopic Instrument (DESI), and undertaken a number of research projects covering numerical simulations, theoretical modelling, data processing, and cosmological measurements.