Resonant shattering flares in black hole-neutron star and binary neutron star mergers

Duncan Neill, David Tsang, Hendrik Van Eerten, Geoffrey Ryan, William G. Newton

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Resonant shattering flares (RSFs) are bursts of gamma-rays expected to be triggered by tidal resonance of a neutron star (NS) during binary inspiral. They are strongly dependent on the magnetic field strength at the surface of the NS. By modelling these flares as being the result of multiple colliding relativistic shells launched during the resonance window, we find that the prompt non-thermal gamma-ray emission may have luminosity up to a few ×1048 erg s -1, and that a broad-band afterglow could be produced. We compute the expected rates of detectable RSFs using the BPASS population synthesis code, with different assumptions about the evolution of surface magnetic field strengths before merger. We find the rate of detectable RSFs to be ∼0.0001-5 per year for BHNS mergers and ∼0.0005-25 per year for NSNS mergers, with the lower bound corresponding to surface-field decay consistent with magneto-thermal evolution in purely crustal fields, while the upper bounds are for systems that have longer lived surface magnetic fields supported by flux frozen into the superconducting core. If some of the observed SGRB precursor flares are indeed RSFs, this suggests the presence of a longer lived surface field for some fraction of the NS population, and that we could expect RSFs to be the most common detectable EM counterpart to GW detections of BHNS mergers. The non-detection of an RSF prior to GRB170817A provides an upper bound on the magnetic fields of the progenitor NSs of Bsurf ∼1013.5G.

Original languageEnglish
Pages (from-to)5385-5402
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date17 Jun 2022
Publication statusPublished - 1 Aug 2022

Bibliographical note

Funding Information:
We w ould lik e to thank Elizabeth Stanw ay and Jan Eldridge for useful and informative discussions about the details of BPASS, and Kostas Gourgouliatos for useful discussion about magnetic field evolution. DN is supported by a University Research Studentship Allowance from the University of Bath. DT additionally thanks Brian Morsony, Samaya Nissanke, and Jocelyn Read for useful discussions, as well as the 2018 Fermi Summer School, for insight into Fermi /GBM data analysis. HJvE acknowledges partial support by the European Union Horizon 2020 programme under the AHEAD2020 project (grant agreement number 871158). GR's research at Perimeter Institute is supported in part by the Go v ernment of Canada through the Department of Innovation, Science and Economic Development and by the Province of Ontario through the Ministry of Colleges and Uni versities. WGN ackno wledges support from NASA grant 80NSSC18K1019.


  • black hole - neutron star mergers
  • dense matter
  • gamma-ray bursts
  • gravitational waves
  • neutron star mergers
  • stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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