Tidal Disruption Events

Repeating Partial TDEs: Evolution over Multiple Outbursts

Stars grazing SMBHs on bound orbits may survive tidal disruption. Using 3D hydrodynamic simulations, We show that Sun-like stars lose progressively more mass in each encounter and are doomed to complete disruption, producing numerous weak flares followed by exponentially brightening luminous flares.

Repeating Partial TDEs: Lessons Learned from ASASSN-14ko

Inspired by the discovery of the periodic nuclear transient ASASSN-14ko, We studied the disruption and fallback of stars on eccentric orbits around SMBHs. I show that eccentric TDEs can produce significantly shorter-lived flares than parabolic TDEs, and that the lack of amplitude evolution in ASASSN-14ko favors an evolved star on a grazing orbit.

Repeating Partial TDEs: Implications from the Missing Third Flares

TDE 2020vdq and 2022dbl are two repeating partial TDE candidates each exhibiting only two observed flares. We show that the missing third flare is most likely due to the star being completely disrupted after the second encounter, providing constraints on the star’s internal structure and the original orbital parameters.

Type Ia Supernovae

SN 2022joj: A Peculiar SN Ia from an Asymmetric Helium-shell Double Detonation

SN 2022joj is a peculiar SN Ia showing dramatic red-blue color evolution on the rise. Its early-time and late-time observables independently point to an asymmetric double detonation of a sub-Chandrasekhar-mass white dwarf, with a viewing angle opposite the ignition point of the shell detonation.

SN 2020jgb: A Peculiar SN Ia Triggered by a Thick-Helium-shell Detonation

SN 2020jgb is a peculiar SN Ia whose unusually red colors, strong blue line blanketing, and prominent helium absorption in the NIR are best explained by a thick helium-shell (~0.1 solar mass) detonation atop a sub-Chandrasekhar-mass white dwarf.

ML for Transient Astronomy

LS-PSC: Morphological Star-Galaxy Classification for Legacy Surveys

A supervised machine learning approach using XGBoost to separate point sources from resolved galaxies in DESI Legacy Surveys (LS). The LS Point Source Catalog (LS-PSC) provides classification scores for ~3 billion sources, achieving superior accuracy compared to traditional morphological typing and enabling real-time extragalactic transient identification.

Adopted By

• La Silla Schmidt Southern Survey (LS4)
• DECam DESI Transient Survey (2DTS)
• Fast and Fortunate for FRB Follow-up (F4)

Open-source Software for Data Processing

HostSub_GP: Galaxy Background Removal in Transient Spectroscopy

A powerful new framework (powered by JAX) for precise host-galaxy subtraction in long-slit transient spectroscopy. It leverages archival imaging and Gaussian-process modeling to build high-fidelity models of galaxy light, enabling robust background removal in complex environments and substantially outperforming traditional techniques.

Publications

• L. A. Kwok, C. Liu, S. W. Jha, et al., 2025, arXiv:2510.09760.
• L. A. Kwok, S. Schulze, C. Liu, et al., 2025, Transient Name Server AstroNote, 129, 1.