Observational Cosmology, Galaxy Formation and Evolution


Galaxies, along with their gas, stars, and dust, are the primary visible manifestations of structure in the Universe. Understanding how galaxies form and evolve is one of the key challenges in astrophysics, requiring insights from stellar populations, gravitational dynamics, gas physics, active galactic nuclei (AGN), computer simulations, and
cosmology. Research in this field spans scales from studying individual stars in the Milky Way to analyzing the bulk properties of millions of distant galaxies.

The galaxy research program at KIAA is focused on uncovering the complex processes that govern galaxy formation and evolution across cosmic time. A significant component of our work involves the multiband photometric and spectroscopic analysis of galaxies, where we use data from diverse wavelengths to investigate galaxies' physical properties, including their stellar populations, interstellar medium (ISM), star formation rates, supermassive black holes (SMBH), and dark matter content. To achieve this, we leverage data from major observational facilities such as JWST, CSST, FAST, LAMOST, and DESI to analyze galaxies on a broad scale, from nearby systems to the most distant objects in the universe. These comprehensive datasets allow us to explore a wide range of phenomena, including the behavior of galaxies in different environments and epochs.

A major focus of our research is understanding the growth of supermassive black holes and the impact of AGN feedback on galaxy evolution, particularly through the study of the ISM. By analyzing the ISM, we aim to constrain how supermassive black holes regulate star formation and gas dynamics within galaxies. This includes research on
star formation in quasars, where we examine how AGN activity and intense star formation co-exist, shaping the evolution of these extreme galaxies. Furthermore, we study galaxies at redshifts ≥ 6, representing some of the earliest cosmic structures. These high-redshift galaxies are critical for understanding the conditions in the early universe and the role galaxies played during the epoch of reionization.

Our research also delves into the kinematics of gas and stars and their role in galaxy evolution. By analyzing both molecular gas and neutral hydrogen (HI) in galaxies, we trace gas reservoirs and examine the gas dynamics within galactic disks, revealing how these factors contribute to galaxy morphology and structure. Additionally, we investigate the connections between dark-matter halos, galaxy morphology, baryonic feedback, and satellite galaxy statistics, addressing fundamental questions in both cosmology and galaxy evolution. By focusing on challenges at both large and small scales within the standard cosmological model, we aim to develop a more comprehensive understanding of how galaxies evolve in different environments, from isolated systems to dense galaxy clusters. Together, these studies provide a holistic understanding of galaxies and their crucial role in shaping the structure and evolution of the universe.

Faculty members: Luis C. Ho, Kohei Inayoshi, Fangzhou Jiang, Linhua
Jiang, Yingjie Peng, Jinyi Shangguan, Jing Wang, Ran Wang, Xue-Bing
Wu, Qingjuan Yu