SkyPy: A package for modelling the Universe

TL;DR

SkyPy is an open-source Python package that enables comprehensive simulations of the astrophysical sky, integrating physical and empirical models for various cosmological observables and facilitating end-to-end astrophysical data generation.

Contribution

It introduces a modular, configurable framework for simulating diverse astrophysical phenomena, with a focus on interoperability and community-driven development.

Findings

Provides functions for galaxy properties like luminosity functions and redshift distributions.

Supports end-to-end simulations with a YAML-based configuration system.

Fosters development of correlated cosmological probe simulations.

Abstract

SkyPy is an open-source Python package for simulating the astrophysical sky. It comprises a library of physical and empirical models across a range of observables and a command-line script to run end-to-end simulations. The library provides functions that sample realisations of sources and their associated properties from probability distributions. Simulation pipelines are constructed from these models using a YAML-based configuration syntax, while task scheduling and data dependencies are handled internally and the modular design allows users to interface with external software. SkyPy is developed and maintained by a diverse community of domain experts with a focus on software sustainability and interoperability. By fostering development, it provides a framework for correlated simulations of a range of cosmological probes including galaxy populations, large scale structure, the cosmic microwave background, supernovae and gravitational waves. Version 0.4 implements functions that model various properties of galaxies including luminosity functions, redshift distributions and optical photometry from spectral energy distribution templates. Future releases will provide additional modules, for example, to simulate populations of dark matter halos and model the galaxy-halo connection, making use of existing software packages from the astrophysics community where appropriate.