A Photometric Classifier for Tidal Disruption Events in Rubin LSST

Abstract

Tidal Disruption Events (TDEs) are astrophysical phenomena arising when stars are disrupted by supermassive black holes. The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), with its unprecedented depth and cadence, will detect thousands of TDEs, motivating the need for robust photometric classifiers capable of efficiently distinguishing these events from other extragalactic transients. We aim to develop and validate a machine learning pipeline for photometric TDE identification in LSST-scale datasets. Our classifier is designed to provide high precision and recall, enabling the construction of reliable TDE catalogs for multi-messenger follow-up and statistical studies. Using the second Extended LSST Astronomical Time Series Classification Challenge (ELAsTiCC2) dataset, we fit Gaussian Processes (GP) to light curves for feature extraction (e.g., color, rise/fade times, GP length scales). We then train and tune boosted decision-tree models (XGBoost) with a custom scoring function emphasizing high-precision recovery of TDEs. Our pipeline is tested on a diverse simulation of transient and variable events, including supernovae, active galactic nuclei, and superluminous supernovae. We achieve high precision (up to 95%) while maintaining competitive recall (about 72%) for TDEs, with minimal contamination from non-TDE classes. Key predictive features include post-peak colors and GP hyperparameters, reflecting characteristic timescales and spectral behaviors of TDEs. Our photometric classifier provides a practical and scalable approach to identifying TDEs in forthcoming LSST data. By capturing essential color and temporal properties through GP-based feature extraction, it enables efficient construction of clean TDE candidate samples.