Are stellar–mass binary black hole mergers isotropically distributed?

Stiskalek, R., Veitch, J. and Messenger, C. (2021) Are stellar–mass binary black hole mergers isotropically distributed? Monthly Notices of the Royal Astronomical Society, 501(1), pp. 970-977. (doi: 10.1093/mnras/staa3613)

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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.

Item Type:Articles
Additional Information:JV was partially supported by STFC grant ST/K005014/1 and JV and CM are supported by the Science and Technology Research Council (grant No. ST/ L000946/1).
Glasgow Author(s) Enlighten ID:Messenger, Dr Christopher and Veitch, Dr John
Authors: Stiskalek, R., Veitch, J., and Messenger, C.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Monthly Notices of the Royal Astronomical Society
Publisher:Oxford University Press
ISSN (Online):1365-2966
Published Online:21 November 2020
Copyright Holders:Copyright © 2020 The Author(s)
First Published:First published in Monthly Notices of the Royal Astronomical Society 501(1): 970-977
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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