EXP: a Python/C++ package for basis function expansion methods in galactic dynamics

TL;DR

EXP is an open-source Python/C++ library that facilitates basis function expansion methods for complex galactic simulations, enabling seamless analysis and discovery of dynamical signals in N-body systems.

Contribution

The paper introduces EXP, a versatile basis function expansion toolkit that connects theoretical models, simulations, and observations in galactic dynamics.

Findings

Supports complex, multi-component galaxy models

Provides a non-parametric time series analysis technique

Enables automated dynamical signal discovery

Abstract

We present the public release of EXP, a basis function expansion C++ library and Python package for running N-body galactic simulations and dynamical discovery. EXP grew out of the need for methodology that seamlessly connects theoretical descriptions of dynamics, N-body simulations, and compact descriptions of observed data. EXP decomposes a galaxy into multiple bases for a variety of scales and geometries and is thus able to represent arbitrarily complex simulations with many components (e.g., disk, bulge, dark matter halo, satellites). pyEXP provides a full Python interface to the EXP C++ libraries. Example workflows based on previously published work are available and distributed as accompanying examples and tutorials. The examples and tutorials flatten the learning curve for adopting basis function expansion tools to generate and analyze the significance of coefficients and discover dynamical relationships using time series analysis. The current release uses a powerful, non-parametric technique for time series analysis that decomposes basis function expansion coefficients into interpretable components without assuming a specific model structure. This enables the automated discovery of dynamical signals from simulations. We provide a full online manual hosted by Read the Docs.