Posterior samples of source galaxies in strong gravitational lenses with score-based priors
This addresses the problem of quantifying accurate priors for astronomers studying strong gravitational lenses, though it appears incremental as it applies an existing method to a specific domain.
The paper tackled the challenge of inferring accurate posteriors for high-dimensional representations of gravitationally-lensed source galaxies by using a score-based model to encode priors, resulting in independent posterior samples that model data nearly to the noise level.
Inferring accurate posteriors for high-dimensional representations of the brightness of gravitationally-lensed sources is a major challenge, in part due to the difficulties of accurately quantifying the priors. Here, we report the use of a score-based model to encode the prior for the inference of undistorted images of background galaxies. This model is trained on a set of high-resolution images of undistorted galaxies. By adding the likelihood score to the prior score and using a reverse-time stochastic differential equation solver, we obtain samples from the posterior. Our method produces independent posterior samples and models the data almost down to the noise level. We show how the balance between the likelihood and the prior meet our expectations in an experiment with out-of-distribution data.