My main research is on cosmology. Specifically, I use large galaxy surveys including BOSS, eBOSS, DESI, PFS, Euclid and so on to reveal the physical origin of the accelarating expansion of the Universe. In the standard cosmological paradigm, General Relativity (GR) is assumed to be the theory of gravity on all scales. According to GR, the expansion of universe should have slowed down. However, the accelerating expansion of our universe was first discovered in 1998 by Supernovae (SN) measurements, which was awarded a Nobel prize in physics in 2011, and later independently confirmed by observations of the Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) of the universe.
The cosmic acceleration is one of the most challenging problems in theoretical physics, and it may suggest that GR, as well as the standard cosmology model based on GR, needs to be modified on cosmological scales (or from another point of view, there exists an unknown energy component, Dark Energy (DE) in the framework of GR). Actually, assuming GR on all scales is a significant extrapolation of our limited knowledge of gravity, and GR remains untested on cosmologically large and small scales using conventional methods.