Approximate the Simulator, Not the Inference: Using Converging Hamiltonian Monte Carlo for Flexible SBI in Astronomy
- đ¤ Speaker: Matthew O'Callaghan (IoA, Cambridge)
- đ Date & Time: Monday 10 February 2025, 16:00 - 17:00
- đ Venue: Martin Ryle Seminar Room, KICC
Abstract
Reliably including computationally intensive simulators with intractable densities in an inference problem is of paramount importance in astronomy. In this talk, I present a normalizing flow architecture that can replace intractable simulators in Bayesian models, while guaranteeing fast convergence of the No U-Turn Sampler variant of Hamiltonian Monte Carlo (HMC) to the posterior distribution. I discuss the limitations of using flow-based methods in HMC , and illustrate examples of a correct implementation for toy examples. I conclude by illustrating its use for estimating interstellar extinction from stellar colours.
Series This talk is part of the Astro Data Science Discussion Group series.
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Monday 10 February 2025, 16:00-17:00