Neutron Star–Black Hole Coalescence Rate Inferred from Macronova Observations
- Key Laboratory of dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China)
- TianQin Research Center for Gravitational Physics, Sun Yat-sen University, Zhuhai 519082 (China)
Neutron star–black hole (NS–BH) coalescences are widely believed to be promising gravitational-wave sources in the era of advanced detectors of LIGO/Virgo, but the rate of this population is highly uncertain due to the lack of direct detection of such binaries. There is growing evidence for the connection between the observed three luminous macronova (also known as kilonova) events and NS–BH mergers. In this work, we propose, for the first time based on such a link, a fiducial lower limit of NS–BH coalescence rate density R{sub nsbh} ≈18.8{sub −8.6}{sup +12.5} Gpc{sup −3} yr{sup −1} (θ{sub j}/0.1rad){sup −2}, where θ{sub j} is the typical half-opening angle of the GRB ejecta. After marginalizing over distributions of black hole masses and spins, we find a rate density R{sub nsbh}⩾10{sup 2} Gpc{sup −3} yr{sup −1}, depending upon the equation of state (EoS) of NS material and the properties of the NS–BH system. With the O1 non-observation by advanced LIGO, we show a preference for NS–BH systems with a stiffer NS EoS and a larger contribution from low-mass/high-spin BHs. Our estimate predicts the first detection of an NS–BH system can be as early as the late O2 run or the early O3 run. We expect that future multi-messenger observations can much better constrain NS–BH systems’ properties.
- OSTI ID:
- 22872578
- Journal Information:
- Astrophysical Journal Letters, Vol. 844, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United Kingdom
- Language:
- English
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