Extracting Equation of State Parameters from Black Hole-Neutron Star Mergers

Benjamin D. Lackey, Koutarou Kyutoku, Masaru Shibata, Patrick R. Brady, John L. Friedman


The late inspiral, merger, and ringdown of a black hole-neutron star (BHNS) system can provide informa-

tion about the neutron-star equation of state (EOS). Candidate EOSs can be approximated by a parametrized

piecewise-polytropic EOS, and we report results from a large set of BHNS inspiral simulations that systemati-

cally vary two parameters. To within the accuracy of the simulations, we find that a single physical parameter

Λ, describing its deformability, can be extracted from the late inspiral, merger, and ringdown waveform. This

parameter is related to the radius, mass, and l = 2 Love number, k2, of the neutron star by Λ = 2k2R5/3M5 , NS

and it is the same parameter that determines the departure from point-particle dynamics during the early inspi- ral. Using various configurations of a single Advanced LIGO detector, we find that Λ1/5 or equivalently R can be extracted to 10–40% accuracy from single events for mass ratios of Q = 2 and 3 at a distance of 100 Mpc, while with the proposed Einstein Telescope, EOS parameters can be extracted to accuracy an order of magnitude better. 

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DOI: https://doi.org/10.17307/wsc.v0i0.80


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