Qinxun Li is a PhD candidate at University of Utah. His research focuses on the measurement of Baryon Acoustic Oscillations (BAO) from large-scale structure surveys. He is actively involved with DESI, especially the galaxy/quasar clustering working group, and co-leads the BAO topical group for the DR3 analysis. Beyond BAO, he is also interested in various cosmological and astrophysical topics, including galaxy-halo connection and gravitational lensing.
Title: Probing evolution of dark energy through galaxy surveys
Abstract: Recent galaxy oscillation distance measurements from the DESI survey, combined with CMB and supernova data, show a 3-4 sigma preference for dynamical dark energy over LambdaCDM. As low-redshift BAO approaches the cosmic variance floor, independent geometric probes at higher redshifts are needed to validate this result and break model degeneracies. In this talk, I will first present the principles of the DESI BAO analysis and discuss the nature of the dynamical dark energy evidence. I will then introduce the Kinematic Lensing Ratio (KiLeR, arXiv:2604.26015), a geometric probe that combines weak lensing shear ratios with intrinsic galaxy shapes reconstructed from disk kinematics to mitigate dominant weak-lensing systematic errors. I will show KiLeR’s statistical potential for constraining dark energy through a forecast for the Roman Space Telescope.