Constraining the Gravitational-Wave Afterglow From a Binary Neutron Star Coalescence
Binary neutron star mergers are rich laboratories for physics, accessible with ground-based interferometric gravitational-wave detectors such as the Advanced LIGO and Advanced Virgo. If a neutron star remnant survives the merger, it can emit gravitational waves that might be detectable with the current or next generation detectors. The physics of the long-lived post-merger phase is not well understood and makes modelling difficult. In particular the phase of the gravitational-wave signal is not well modelled. In this paper, we explore methods for using long duration post-merger gravitational-wave signals to constrain the parameters and the properties of the remnant. We develop a phase-agnostic likelihood model that uses only the spectral content for parameter estimation and demonstrate the calculation of a Bayesian upper limit in the absence of a signal. With the millisecond magnetar model, we show that for an event like GW170817, the ellipticity of a long-lived remnant can be constrained to less than about 0.5 in the parameter space used.
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Received: 05 September 2019; Revision received: 16 January 2020; Accepted: 16 January 2020; Published: 22 January 2020. We are grateful to Ling Sun, Joe Romano, David Keitel, and Paul Schale for useful discussion and comments. We also thank Tyson Littenberg for insightful comments and suggestions that improved the paper. SB acknowledges support by the Hoff Lu Fellowship at the University of Minnesota, and by NSF grant PHY-1806630. MWC is supported by the David and Ellen Lee Postdoctoral Fellowship at the California Institute of Technology. PDL is supported by ARC Future Fellowship FT160100112 and ARC Discovery Project DP180103155. ET and CT are supported by CE170100004. ET is supported by FT150100281. The authors are thankful for the computing resources provided by LIGO Laboratory. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0757058. All posterior corner plots were made with CHAINCONSUMER (Hinton 2016). The code for the analysis in this paper is available upon request. A public release is being planned for the near future. This paper has been assigned document number LIGO-P1900107.
Published - staa181.pdf
Submitted - 1909.01934.pdf