[1109.3402] Extracting equation of state parameters from black hole-neutron star mergers. I. Nonspinning black holes

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

Date: 15 Sep 2011

Abstract: The late inspiral, merger, and ringdown of a black hole-neutron star (BHNS) system can provide information about the neutron-star equation of state (EOS). Candidate EOSs can be approximated by a parametrized piecewise-polytropic EOS above nuclear density, matched to a fixed low-density EOS; and we report results from a large set of BHNS inspiral simulations that systematically vary two parameters. To within the accuracy of the simulations, we find that, apart from the neutron-star mass, a single physical parameter Lambda, 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, k_2, of the neutron star by Lambda = 2k_2 Rˆ5/3M_{NS}ˆ5, and it is the same parameter that determines the departure from point-particle dynamics during the early inspiral. Observations of gravitational waves from BHNS inspiral thus restrict the EOS to a surface of constant Lambda in the parameter space, thickened by the measurement error. Using various configurations of a single Advanced LIGO detector, we find that neutron stars are distinguishable from black holes of the same mass and that Lambdaˆ{1/5} 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.

abs pdf

Sep 16, 2011

1109.3402 (/preprints)
2011-09-16, 10:23 [edit]

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