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2026.08.12

Strong lensing meets stellar dynamics: from cosmology to galaxy evolution

Time-delay cosmography with strongly lensed quasars measures the Hubble constant independently of the distance ladder and the CMB, but its accuracy is limited by the mass-sheet degeneracy (MSD), which lensing data alone cannot break. Stellar dynamics of the lens galaxy provides the missing information. I will present GLaD, a GPU-accelerated framework for self-consistent joint modeling of strong...

2026.07.21

A Semi-Analytical Loss Cone Theory for Tidal Disruption Event Rates Around Kerr Black Holes

I discuss how strong gravity shapes tidal disruption event rates around spinning Kerr black holes. Spin makes the disruption and direct-capture boundaries depend on orbital inclination, turning the classical loss-cone problem into a two-dimensional diffusion problem in angular-momentum magnitude and orientation. I show a metric-to-rate calculation that connects relativistic orbital and tidal dy...

2026.07.15

杨晓峰报告

2025年DESI观测结果明显支持动态暗能量；DESI和JWST等观测挑战了ΛCDM模型，我们尝试探索其它非标准模型如Kolb滑行宇宙，即匀速膨胀宇宙模型。这个模型也需要暗能量，但其底层动力学框架仍然空白。我们提出熵起源的滑行宇宙暗能量模型，发现非广延统计物理中的Tsallis熵恰好满足该暗能量的熵起源。另一方面，宇宙学原理和广义相对论都精确成立是ΛCDM模型的两大基石，也是暗能量存在的逻辑前提。近年有Ia超新星、星系四点关联函...

2026.07.21

Mapping the large scale structure of the Universe in radio wavelength with MeerKLASS and SKAO

Neutral hydrogen intensity mapping (HIIM) has become an emerging alternative probe of the cosmic large scale structure of the Universe. Radio telescopes can be used to map the distribution of the 21cm emission line of neutral hydrogen, yielding intrinsically spectroscopic surveys of LSS. In this talk, I will review the progress of the HIIM surveys of LSS, focusing in particular on the MeerKLASS...

2026.07.03

New Theoretical Insights into Black Hole Coronae

What powers the hard, non-thermal X-rays from accreting black holes has been a longstanding mystery. In this talk, I will address the underlying question of what energizes the plasma of the Comptonizing “corona” against the strong inverse Compton cooling losses with first-principle particle-in-cell simulations of magnetic reconnection subject to radiative cooling losses in magnetized electron...

2026.06.29

Linking Plasma Dynamics, Particle Acceleration, and Multi-Messenger Emission in Active Galactic Nuclei

Recent advances in multi-messenger and time-domain astronomy are opening a new window onto the high-energy universe and transforming our understanding of active galactic nuclei (AGNs). Observations across photons, neutrinos, and cosmic rays now make it possible to probe how supermassive black holes power some of the most extreme plasma environments in nature, including jets, coronae, and accret...

2026.06.08

The coevolution of black holes, galaxies and dark matter halos

Current cosmology provides the initial and boundary conditions to understand the formation and evolution of objects across the whole structure hierarchy. I will describe a model for the coevolution of black holes, galaxies and dark matter halos in the current cosmology provides the initial and boundary conditions to understand the formation and evolution of objects across the whole structure hi...

2026.05.27

Charaterizing Cosmic Acceleration with Geometric Probes from Galaxy Surveys

The underlying physics of cosmic acceleration remains one of the most profound mysteries in cosmology after almost three decades since its discovery from Type Ia supernovae. Galaxy surveys, such as Sloan Digital Sky Survey (SDSS) and Dark Energy Spectroscopic Instrument (DESI), have provided us with independent evidence for cosmic acceleration. Moreover, recent DESI DR2 measurements of Baryon A...

2026.05.22

Time Delay cosmography and the Hubble tension

Strongly lensed quasars can be used to measure the Hubble constant, provided the time delays between the lensed images can be measured. The method depends on a model for the lensing galaxy but is fully independent of any other method to measure H0. It is therefore crucial to confirm (or not) the Hubble tension. The method comes however with its own systematics that are currently addressed by th...

2026.06.18

Physics-Informed Machine Learning for precise and accurate weak lensing shear estimation

Weak gravitational lensing has served as an important probe for large-scale structure and cosmology for decades. Stage-IV surveys require both sub-percent calibration accuracy and high statistical precision for WL shear estimation, yet traditional estimators struggle with realistic galaxy complexity while machine-learning methods often introduce biases. I will introduce a physics-informed machi...