The colorful and diverse zoo of galaxies (Image credit: NASA/ESA/A. EVANS)

Galaxies, the building blocks of the cosmic large-scale structure, contain millions to up to several trillion stars (with various colors, masses etc) with typical sizes of several thousands to hundred thousands light years, and are believed to host (at least) one supermassive black holes (SMBH; whose masses are of millions to billions times of our Sun) in their centers. The average density of a typical galaxy (e.g., our Milky Way) is about several million times larger than the average density of the Universe, making it in the highly non-linear regime of the cosmic structure formation due to gravitational perturbations.  In addition to gravity, other small scale physical processes, e.g., gas recycling involving gas accretion through intergalactic/circumgalactic medium, star formation and evolution, outflow driven either by supernovae or by the center volcano (i.e., the active SMBH), also play important roles in making the colorful and diverse zoo of galaxies. Strikingly, the center SMBH mass is tightly correlated with its host galaxy properties (e.g., the bulge mass, stellar velocity dispersion), though the spatial size of former is about nine orders of magnitude smaller than that of the latter; the tight correlations indicate that the center monster and its host should co-evolve over the cosmic time. Understanding the formation and evolution of galaxies, the cosmic star formation history and growth history of SMBHs, and using them as a probe of the cosmological formation models are the key questions of galaxy research.

The galaxy studies in DoA, Xiamen University focus on the following areas: the intergalactic/circumgalactic/interstellar medium and the cycle of matter and energy in galaxies; the galactic star formation and quenching; the formation and evolution history of galaxies; the cosmic growth history of SMBHs and their feedbacks. Our research uses theoretical modeling, numerical simulations, and multi-wavelength surveys, e.g., including the Five-hundred-meter Aperture Spherical Telescope (FAST), the Subaru Prime Focus Spectrograph project (PFS), the EAO/James Clark Maxwell Telescope (JINGLE and MALATANG projects), the IRAM telescopes, and future facilities the Thirty Meter Telescope (TMT), the Chinese Space Station Telescope (CSST), the Square Kilometer Array (SKA) and the Legacy Survey of Space and Time (LSST).

Faculties: Taotao Fang, Yu Gao, Junfeng Wang, Jianfeng Wu, Mouyuan Sun