Astronomy Tea Talk

Speaker 1: Jackie Blaum

Title: Neural Simulation-Based Inference for Detached Eclipsing Binaries with Informed Hierarchical Priors

Abstract: Detached eclipsing binaries (DEBs) provide direct constraints on stellar and orbital parameters. In practice, traditional inference relies on computationally intensive forward modeling and radial velocity (RV) information, which limits homogeneous analyses to relatively small samples. Modern time-domain surveys have identified hundreds of thousands of photometric DEBs without RV follow-up, motivating scalable methods that rely on photometry alone. Here we present a multimodal amortized neural posterior estimator for DEB inference that combines survey-realistic light curves, broadband spectral energy distributions, and Gaia parallaxes within a hierarchical prior framework. The generative model enforces broad consistency with stellar evolution through MIST isochrones and incorporates realistic survey cadence and noise patterns to produce training data reflective of real observations. A conditional normalizing flow approximates the full 16-dimensional posterior distribution. Across nearly 5,000 held-out simulations, the amortized posterior recovers parameters accurately and yields calibrated uncertainties, verified through simulation-based calibration and empirical coverage tests. Generating the entire training set requires computational effort comparable to a traditional MCMC analysis of a single system. Once trained, inference for new systems is effectively instantaneous. This framework enables scalable DEB analysis in the era of LSST and other large time-domain surveys.

Speaker 2: Scott Lucchini

Title: The Circumgalactic Medium at 200 pc

Abstract: The circumgalactic medium (CGM) plays a crucial role in the baryon cycle by mediating all of the gas flows in and out of the galaxy. However, simulating this region is difficult due to its immense volume and low densities. Fixed spatial resolution is an excellent tool to overcome this problem. In this talk, I will introduce a new suite of cosmological zoom simulations with 200 pc resolution covering the inner CGM of a Milky Way-mass galaxy, utilizing the full IllustrisTNG galaxy formation model. At this high resolution, we find increased turbulent velocities, many small, cold cloudlets, and an intricately structured hot phase.