Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
Author(s)Aggarwal, Neerja; Buikema, Aaron; Donovan, Frederick J; Eisenstein, Robert Alan; Essick, Reed Clasey; Fernandez Galiana, Alvaro-Miguel; Fritschel, Peter K; Gras, Slawomir; MacInnis, Myron E; Martynov, Denis; Mason, Kenneth R; Matichard, Fabrice; Mavalvala, Nergis; Miller, John; Vitale, Salvatore; Weiss, Rainer; Yu, Haocun; ... Show more Show less
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The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting mass of the dynamical ejecta to estimate its contribution (without the effects of wind ejecta) to the corresponding kilonova light curves from various models. The distributions of dynamical ejecta mass range between M ej = 10 -3 - 10 -2 M ⊙ for various equations of state, assuming that the neutron stars are rotating slowly. In addition, we use our estimates of the dynamical ejecta mass and the neutron star merger rates inferred from GW170817 to constrain the contribution of events like this to the r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if ≳10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.
DepartmentMassachusetts Institute of Technology. Department of Aeronautics and Astronautics; Massachusetts Institute of Technology. Department of Mechanical Engineering; Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science; MIT Kavli Institute for Astrophysics and Space Research
The Astrophysical Journal
American Astronomical Society
Abbott, B. P., R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams, et al. “Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817.” The Astrophysical Journal 850, no. 2 (December 1, 2017): L39.
Final published version