Our research aims are to study the formation, evolution, and structure of galaxies. A central theme of the group’s research for many years has been stellar clusters and the structure of the Milky Way.
LAMOST and the Galactic structure
Characterising and classifying the stars around us is crucial if we are to use them to study the structure of our galaxy. Spectroscopic surveys such as LAMOST are providing spectra for millions of stars, but only by determining properties such as stellar types (and hence distances) and ages will we be fully able to exploit these datasets. Meanwhile, we are able to discover a large sample of Hyper-velocity stars, which will provide unique constraints on the shape of the potential of the Galaxy’s dark matter halo. (Jing Zhong, Martin Smith)
Open clusters(OCs) have long been used to trace the structure and evolution of the Galactic disk. Open clusters have relatively large age & distance spans and can be relatively accurately dated; the spatial distribution, kinematical properties and metalicities of OCs provide critical constraints on the overall structure and chemical and dynamical evolution of the galactic disk;(Li Chen)
The present state of our galaxy can tell us a lot about how it has formed and evolved. In particular the stellar halo contains satellite galaxies and relics of accretion events, resulting in many substructures and streams. By discovering and analysing these substructures we can probe the details of hierarchical assembly and confront predictions from cosmological simulations. (Martin Smith)
Galactic Chemical Evolution (GCE) model
GCE is the study of the evolution in time and space of the abundances of the chemical elements in the interstellar medium (ISM) in galaxies. As the template of disk galaxies, the Milky Way galaxy is the best sample in testing the usefulness and importance of the GCE theory. By comparing the GCE results with the observations, we are able to understand how our Galaxy was assembled, what is the history of star formation and gas accretion during the evolution of the Galaxy.
In spite of great success of the Galactic Chemical Evolution model in explaining the current observed characteristics of the Milky Way and nearby galaxies, there are varieties of phenomena need to be addressed in more detail, especially in the framework of hierarchical galaxy formation and in the new paradigm of radial migration proposed during the past years. Also large sky surveys as currently undergoing LAMOST and SDSS-IV (APOGEE), will provide spectra for millions of stars. The new data have already demonstrated that our Milky Way Galaxy is spatially and kinematically complex, and composed of different components for both disk and halo. New GCE theory is required to explain in more detail for the fine structures of our Galaxy. (Ruixiang Chang, Jun Yin, Jinliang Hou, Jian Fu)
Formation and evolution of galaxies
Statistical study of galaxies and AGNs
Large scale galaxy surveys such as SDSS have recently released large amounts of datasets. Group members have been involved in using these to investigate various statistical properties of observed galaxy populations, such as the luminosities and sizes of different galaxy types, and the correlations between the properties of AGNs and their host galaxies.
Our group members are deeply involved in the MaNGA program of SDSS IV. (Zhengyi Shao, Shiyin Shen)
SHAO is a joint institute of SDSS IV.
Semi-analytic models of disk galaxies
Understanding how galaxy disks form is the key to understand how a galaxy forms. It is believed that disk dominated galaxies such as spirals are formed by the cooling of baryonic matter inside a virialized dark halo. Semi-analytic models (SAM) are a powerful tool in studying this process. The SAM method gives a detailed description of how the angular momentum in a protogalaxy is redistributed, how the disk grows, how star formation progresses, and can elucidate the role of galactic winds, and feedback, amongst many other effects. Researchers in the group have been actively involved in tackling these important research problems.(Jian Fu, Jianling Gan)
SDSS IV collaboration
Our group are actively involved in SDSS IV collaborations.
In addition to above research topics, we also have fruitful international co-operations with Germany (MPA), Canada (DAO), France (IAP), and the USA (UMASS) through visiting scholars, student exchanges, and joint observation programs. One can learn more about our research from our publications.