Are stellar--mass binary black hole mergers isotropically distributed?

Abstract

The Advanced LIGO and Advanced Virgo gravitational wave detectors have detected a population of binary black hole mergers in their first two observing runs. For each of these events we have been able to associate a potential sky location region represented as a probability distribution on the sky. Thus, at this point we may begin to ask the question of whether this distribution agrees with the isotropic model of the Universe, or if there is any evidence of anisotropy. We perform Bayesian model selection between an isotropic and a simple anisotropic model, taking into account the anisotropic selection function caused by the underlying antenna patterns and sensitivity of the interferometers over the sidereal day. We find an inconclusive Bayes factor of $1.3:1$, suggesting that the data from the first two observing runs is insufficient to pick a preferred model. However, the first detections were mostly poorly localised in the sky (before the Advanced Virgo joined the network), spanning large portions of the sky and hampering detection of potential anisotropy. It will be appropriate to repeat this analysis with events from the recent third LIGO observational run and a more sophisticated cosmological model.

8 pages, 8 figures. Accepted by MNRAS

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Cited by in corpus (14)

• Search for anisotropic gravitational-wave backgrounds using data from Advanced LIGO and Advanced Virgo's first three observing runs
• Detection of Early-Universe Gravitational Wave Signatures and Fundamental Physics
• Searching for anisotropy in the distribution of binary black hole mergers
• Searching for Cross-Correlation Between Stochastic Gravitational Wave Background and Galaxy Number Counts
• Detection and estimation of the cosmic dipole with the Einstein Telescope and Cosmic Explorer
• An Isotropy Measurement with Gravitational Wave Observations
• Two-dimensional correlation function of binary black hole coalescences
• Fast Likelihood-free Reconstruction of Gravitational Wave Backgrounds
• Bayesian parameter estimation for targeted anisotropic gravitational-wave background
• Boosting gravitational waves: a review of kinematic effects on amplitude, polarization, frequency and energy density
• Dipole Anisotropy in Gravitational Wave Source Distribution
• Combining chirp mass, luminosity distance and sky localisation from gravitational wave events to detect the cosmic dipole
• The directional isotropy of LIGO-Virgo binaries
• Applying Cosmological Principle to Better Probe the Redshift Evolution of Binary Black Hole Merger Rate