Fast, high-fidelity Lyman $\alpha$ forests with convolutional neural networks

Abstract

Full-physics cosmological simulations are powerful tools for studying the formation and evolution of structure in the universe but require extreme computational resources. Here, we train a convolutional neural network to use a cheaper N-body-only simulation to reconstruct the baryon hydrodynamic variables (density, temperature, and velocity) on scales relevant to the Lyman-$\alpha$ (Ly$\alpha$) forest, using data from Nyx simulations. We show that our method enables rapid estimation of these fields at a resolution of $\sim$20kpc, and captures the statistics of the Ly$\alpha$ forest with much greater accuracy than existing approximations. Because our model is fully-convolutional, we can train on smaller simulation boxes and deploy on much larger ones, enabling substantial computational savings. Furthermore, as our method produces an approximation for the hydrodynamic fields instead of Ly$\alpha$ flux directly, it is not limited to a particular choice of ionizing background or mean transmitted flux.

10 pages, 6 figures

References in corpus (5)

• Detecting shock waves in cosmological smoothed particle hydrodynamics simulations
• Detecting shocked intergalactic gas with X-ray and radio observations
• Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum
• HIGAN: Cosmic Neutral Hydrogen with Generative Adversarial Networks
• Simulating intergalactic gas for DESI-like small scale Lymanα forest observations

Cited by in corpus (8)

• The CAMELS project: public data release
• HyPhy: Deep Generative Conditional Posterior Mapping of Hydrodynamical Physics
• LyMAS reloaded: improving the predictions of the large-scale Lyman-α forest statistics from dark matter density and velocity fields
• Ly$\alpha$NNA: A Deep Learning Field-level Inference Machine for the Lyman-$\alpha$ Forest
• Differentiable Cosmological Hydrodynamics for Field-Level Inference and High Dimensional Parameter Constraints
• Modeling the Cosmological Lyman-$\alpha$ Forest at the Field Level
• Neural network emulator to constrain the high-$z$ IGM thermal state from Lyman-$\alpha$ forest flux auto-correlation function
• Bridging Simulations and EFT: A Hybrid Model of the Lyman-Alpha Forest Field