On 2019 April 25, the LIGO Livingston detector observed a compact binary coalescence with signal-to-noise ratio 12.9. The Virgo detector was also taking data that did not contribute to detection due to a low signal-to-noise ratio, but were used for subsequent parameter estimation. The 90% credible intervals for the component masses range from 1.12 to 2.52 M⊙ (1.46–1.87 M⊙ if we restrict the dimensionless component spin magnitudes to be smaller than 0.05). These mass parameters are consistent with the individual binary components being neutron stars. However, both the source-frame chirp mass 1.44+0.02-0.02M⊙ and the total mass 3.4+0.3-0.1M⊙ of this system are significantly larger than those of any other known binary neutron star (BNS) system. The possibility that one or both binary components of the system are black holes cannot be ruled out from gravitational-wave data. We discuss possible origins of the system based on its inconsistency with the known Galactic BNS population. Under the assumption that the signal was produced by a BNS coalescence, the local rate of neutron star mergers is updated to 250–2810 Gpc-3yr-1.
History
Publication title
The Astrophysical Journal Letters
Volume
892
Article number
L3
Number
L3
ISSN
2041-8205
Department/School
School of Natural Sciences
Publisher
Institute of Physics Publishing Ltd.
Place of publication
United Kingdom
Rights statement
Copyright (2020) The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 (CC BY 4.0) licence (https://creativecommons.org/licenses/by/4.0/).