PRECESSION: Dynamics of spinning black-hole binaries with python

TL;DR

PRECESSION is an open-source Python tool that models the complex spin dynamics of precessing black-hole binaries in the post-Newtonian regime, aiding gravitational-wave research and astrophysical studies.

Contribution

It introduces a comprehensive, easy-to-use Python module for simulating black-hole spin precession, inspirals, and merger properties, integrating numerical relativity fitting formulas.

Findings

Provides fast, reliable spin evolution simulations

Enables linking gravitational-wave observations to astrophysical origins

Supports integration with larger astrophysical and gravitational-wave analysis frameworks

Abstract

We present the numerical code PRECESSION: a new open-source python module to study the dynamics of precessing black-hole binaries in the post-Newtonian regime. The code provides a comprehensive toolbox to (i) study the evolution of the black-hole spins along their precession cycles, (ii) perform gravitational-wave driven binary inspirals using both orbit-averaged and precession-averaged integrations, and (iii) predict the properties of the merger remnant through fitting formulae obtained from numerical-relativity simulations. PRECESSION is a ready-to-use tool to add the black-hole spin dynamics to larger-scale numerical studies such as gravitational-wave parameter estimation codes, population synthesis models to predict gravitational-wave event rates, galaxy merger trees and cosmological simulations of structure formation. PRECESSION provides fast and reliable integration methods to propagate statistical samples of black-hole binaries from/to large separations where they form to/from small separations where they become detectable, thus linking gravitational-wave observations of spinning black-hole binaries to their astrophysical formation history. The code is also a useful tool to compute initial parameters for numerical-relativity simulations targeting specific precessing systems. PRECESSION can be installed from the Python Package Index and it is freely distributed under version control on Github, where further documentation is provided.