FLaREON : a fast computation of Ly$\alpha$ escape fractions and line profiles.

We present FLaREON (Fast Lyman-Alpha Radiative Escape from Outflowing Neutral gas), a public python package that delivers fast and accurate Lyman alpha escape fractions and line profiles over a wide range of outflow geometries and properties. The code incorporates different algorithms, such as interpolation and machine learning to predict Lyman alpha line properties from a pre-computed grid of outflow configurations based on the outputs of a Monte Carlo radiative transfer code. Here we describe the algorithm, discuss its performance and illustrate some of its many applications. Most notably, FLaREON can be used to infer the physical properties of the outflowing medium from an observed Lyman alpha line profile, including the escape fraction, or it can be run over millions of objects in a galaxy formation model to simulate the escape of Lyman alpha photons in a cosmological volume.