No tension between assembly models of super massive black hole binaries and pulsar observations

Hannah Middleton*, Siyuan Chen, Walter Del Pozzo, Alberto Sesana, Alberto Vecchio

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
123 Downloads (Pure)


Pulsar timing arrays are presently the only means to search for the gravitational wave stochastic background from super massive black hole binary populations, considered to be within the grasp of current or near-future observations. The stringent upper limit from the Parkes Pulsar Timing Array has been interpreted as excluding (>90% confidence) the current paradigm of binary assembly through galaxy mergers and hardening via stellar interaction, suggesting evolution is accelerated or stalled. Using Bayesian hierarchical modelling we consider implications of this upper limit for a range of astrophysical scenarios, without invoking stalling, nor more exotic physical processes. All scenarios are fully consistent with the upper limit, but (weak) bounds on population parameters can be inferred. Recent upward revisions of the black hole-galaxy bulge mass relation are disfavoured at 1.6σ against lighter models. Once sensitivity improves by an order of magnitude, a non-detection will disfavour the most optimistic scenarios at 3.9σ.

Original languageEnglish
Article number573
JournalNature Communications
Issue number1
Publication statusPublished - 8 Feb 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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