pyEFPE is a Python-based post-Newtonian waveform model for inspiralling precessing-eccentric compact binaries.

If you use pyEFPE in your research, please cite:

G. Morras, G. Pratten, and P. Schmidt, Improved post-Newtonian waveform model for inspiralling precessing-eccentric compact binaries, Phys.Rev.D 111 (2025) 8, 084052, arXiv:2502.03929.

You can use the following BibTeX entry:

@article{Morras:2025nlp,
    author = "Morras, Gonzalo and Pratten, Geraint and Schmidt, Patricia",
    title = "{Improved post-Newtonian waveform model for inspiralling precessing-eccentric compact binaries}",
    eprint = "2502.03929",
    archivePrefix = "arXiv",
    primaryClass = "gr-qc",
    reportNumber = "IFT-UAM/CSIC-25-12",
    doi = "10.1103/PhysRevD.111.084052",
    journal = "Phys. Rev. D",
    volume = "111",
    number = "8",
    pages = "084052",
    year = "2025"
}

To install pyEFPE, navigate to the root directory of the repository (where setup.py is located) and run:

pip install .

To generate a frequency-domain waveform using pyEFPE, try the following example:

# Import required packages
import pyEFPE
import numpy as np

# Define binary parameters (for additional details see pyEFPE/waveform/EFPE.py)
params = {
    'mass1': 2.4,       # Mass of companion 1 (solar masses)
    'mass2': 1.2,       # Mass of companion 2 (solar masses)
    'e_start': 0.7,     # Initial eccentricity
    'spin1x': -0.44,    # Spin components of companion 1
    'spin1y': -0.26,
    'spin1z': 0.48,
    'spin2x': -0.31,    # Spin components of companion 2
    'spin2y': 0.01,
    'spin2z': -0.84,
    'inclination': 1.57,# Initial binary inclination (radians)
    'f22_start': 10,    # Starting (simulation) waveform frequency of GW 22 mode (Hz)
}

# Initialize pyEFPE waveform model
wf = pyEFPE.pyEFPE(params)

# Define frequency array for waveform generation
freqs = np.arange(20, 1024, 1/128)

# Compute frequency-domain gravitational wave polarizations
hp, hc = wf.generate_waveform(freqs)

You can visualize this waveform using the following code:

from matplotlib import pyplot as plt

plt.figure()
plt.loglog(freqs,  np.abs(hp), 'C0-' , label=r'$|\tilde{h}_+|$')
plt.loglog(freqs,  np.abs(hc), 'C1-' , label=r'$|\tilde{h}_\times|$')
plt.xlabel(r'$f$ [Hz]')
plt.ylabel(r'Frequency domain strain $[\mathrm{Hz}^{-1}]$')
plt.legend()
plt.show()

The installable waveform model is located in the pyEFPE/ folder, while the Tests/ folder contains various examples and tests of the waveform. Most notably, the Tests/model_validation/ directory contains the scripts used to generate most of the model-validation figures from the pyEFPE paper, and the Tests/test_theory/ directory contains Mathematica notebooks and Python scripts used to validate some of the post-Newtonian expressions that the model is based on.

We welcome feedback, bug reports, and feature requests! If you encounter any issues or have suggestions for improvements, please open an issue in the GitHub issue tracker.

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.