Type: Talk
Session: Transient and Variable Star Science I
Author: Charlotte Ward

Abstract: Many of the AGN and transient science cases for LSST rely on accurate identification and characterization of the host galaxies in deep, highly blended fields. While techniques such as difference imaging provide fast extraction of transient light curves, a full scene modeling approach enables simultaneous fitting of host galaxy SEDs, host galaxy morphologies, and transient-host spatial offsets -- essential to the classification of transients as nuclear or `non-nuclear' and to informed host galaxy associations in highly blended fields. In this talk, I will describe a new `time-domain' extension of the Scarlet2 scene modeling and deblending code which exploits additional constraints on variable vs static sources across multi-epoch, multi-band imaging data to extract transient photometry and host galaxy models in crowded fields. Scarlet2 provides the advantages of data-driven priors on galaxy morphologies enabling non-parametric galaxy models, is fully GPU compatible, and can jointly model multi-resolution data for the incorporation of high-resolution space-based imaging. I will demonstrate the methodology on simulated supernova imaging, low resolution Zwicky Transient Facility imaging of tidal disruption events, and LSST-like Hyper Suprime Cam imaging of variable AGN out to z=4 in the COSMOS fields. I will discuss how Scarlet2 scene models enable accurate measurement of host-transient spatial offsets and discuss future applications to the search for `wandering' massive black holes in the era of LSST.