Analysis of galaxy--galaxy strong lensing systems is strongly dependent on any prior assumptions made about the appearance of the source. Here we present a method of imposing a data-driven prior / regularisation for source galaxies based on denoising diffusion probabilistic models (DDPMs). We use a pre-trained model for galaxy images, AstroDDPM, and a chain of conditional reconstruction steps called denoising diffusion reconstruction model (DDRM) to obtain samples consistent both with the noisy observation and with the distribution of training data for AstroDDPM. We show that these samples have the qualitative properties associated with the posterior for the source model: in a low-to-medium noise scenario they closely resemble the observation, while reconstructions from uncertain data show greater variability, consistent with the distribution encoded in the generative model used as prior.
@article{arxiv.2211.04365,
title = {Strong-Lensing Source Reconstruction with Denoising Diffusion Restoration Models},
author = {Konstantin Karchev and Noemi Anau Montel and Adam Coogan and Christoph Weniger},
journal= {arXiv preprint arXiv:2211.04365},
year = {2022}
}
Comments
Accepted for the NeurIPS 2022 workshop Machine Learning and the Physical Sciences; 9 pages, 4 figures