GreyRing
Frequency-domain ringdown toolkit

GreyRing

Python tools for black-hole ringdown analyses based on greybody factors: from SXS validation to controlled injection-recovery tests and public gravitational-wave data.

Get started See examples

What GreyRing does

GreyRing models the frequency-domain black-hole ringdown using greybody factors, with explicit examples for validation, injection studies, and event-level analyses.

Validation

SXS fit

Fit numerical-relativity waveforms.

 Pipeline test

Injection-recovery

Inject a GreyRing signal and recover the remnant parameters with Bilby.

 Data analysis

Real data

Run an event-level workflow with public strain data.

Quick start

git clone https://github.com/romeofelicerosato-prog/GreyRing
cd GreyRing
pip install -e .
python -c "import greyring as gr; print(gr)"

Repository structure

GreyRing/
├── greyring/     # importable Python package
└── examples/     # SXS fits, Bilby injections, real-data runs

Documentation map

Installation

Theory files

Kerr GFs Computation

Citation

If you use GreyRing in scientific works, please cite the relevant GreyRing papers and the external software packages used in your analysis.

GreyRing amplitude model

Modeling the frequency-domain ringdown amplitude of comparable-mass mergers with greybody factors

Romeo Felice Rosato, Sophia Yi, Emanuele Berti, and Paolo Pani

Physical Review D 113, 064060 (2026)

arXiv:2512.15877 · DOI

BibTeX 
@article{Rosato:2025ulx,
  author = {Rosato, Romeo Felice and Yi, Sophia and Berti, Emanuele and Pani, Paolo},
  title = {Modeling the frequency-domain ringdown amplitude of comparable-mass mergers with greybody factors},
  eprint = {2512.15877},
  archivePrefix = {arXiv},
  primaryClass = {gr-qc},
  doi = {10.1103/jqgb-mfg1},
  journal = {Phys. Rev. D},
  volume = {113},
  number = {6},
  pages = {064060},
  year = {2026}
}
GreyRing tests of GR

Novel ringdown tests of general relativity with black hole greybody factors

Romeo Felice Rosato, Francesco Crescimbeni, Sophia Yi, Emanuele Berti, and Paolo Pani

arXiv preprint (2026)

arXiv:2604.11895

BibTeX 
@article{Rosato:2026apq,
  author = {Rosato, Romeo Felice and Crescimbeni, Francesco and Yi, Sophia and Berti, Emanuele and Pani, Paolo},
  title = {Novel ringdown tests of general relativity with black hole greybody factors},
  eprint = {2604.11895},
  archivePrefix = {arXiv},
  primaryClass = {gr-qc},
  month = {4},
  year = {2026}
}