B ilby-MCMC: an MCMC sampler for gravitational-wave inference

Jun 16, 2021
16 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 507 (2021) 2, 2037-2051
  • Published: Aug 28, 2021
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Abstract: (Oxford University Press)
We introduce Bilby-MCMC, a Markov chain Monte Carlo sampling algorithm tuned for the analysis of gravitational waves from merging compact objects. Bilby-MCMC provides a parallel-tempered ensemble Metropolis-Hastings sampler with access to a block-updating proposal library including problem-specific and machine learning proposals. We demonstrate that learning proposals can produce over a 10-fold improvement in efficiency by reducing the autocorrelation time. Using a variety of standard and problem-specific tests, we validate the ability of the Bilby-MCMC sampler to produce independent posterior samples and estimate the Bayesian evidence. Compared to the widely used Dynesty nested sampling algorithm, Bilby-MCMC is less efficient in producing independent posterior samples and less accurate in its estimation of the evidence. However, we find that posterior samples drawn from the Bilby-MCMC sampler are more robust: never failing to pass our validation tests. Meanwhile, the Dynesty sampler fails the difficult-to-sample Rosenbrock likelihood test, over constraining the posterior. For CBC problems, this highlights the importance of cross-sampler comparisons to ensure results are robust to sampling error. Finally, Bilby-MCMC can be embarrassingly and asynchronously parallelized making it highly suitable for reducing the analysis wall-time using a High Throughput Computing environment. Bilby-MCMC may be a useful tool for the rapid and robust analysis of gravitational-wave signals during the advanced detector era and we expect it to have utility throughout astrophysics.
Note:
  • 16 pages, 7 figures, accepted to MNRAS
  • gravitational waves
  • transients: neutron star mergers
  • transients: black hole mergers
  • methods: data analysis
  • stars: black holes
  • stars: neutron
  • Monte Carlo: Markov chain
  • gravitational radiation
  • statistical analysis: Bayesian
  • neutron star: binary