Estimating the contribution of dynamical ejecta in the kilonova associated with GW170817

Research output: Contribution to journalArticlepeer-review

Authors

  • LIGO Scientific Collaboration
  • Virgo Collaboration

Colleges, School and Institutes

External organisations

  • California Institute of Technology
  • Louisiana State University
  • University of Salerno
  • Complesso Universitario di Monte S.Angelo
  • University of Florida
  • Monash University
  • LIGO Livingston Observatory
  • IN2P3
  • University of Sannio at Benevento
  • Albert-Einstein-Institut, Max-Planck-Institut für, Gravitationsphysik
  • University of Mississippi
  • University of Illinois
  • University of Cambridge
  • Institution Nikhef National Institute for Subatomic Physics
  • Massachusetts Institute of Technology
  • Instituto Nacional de Pesquisas Espaciais
  • Facebook
  • Laboratori Nazionali del Gran Sasso
  • Inter-University Centre for Astronomy and Astrophysics India
  • Tata Institute of Fundamental Research
  • University of Wisconsin-Milwaukee
  • Università di Pisa
  • Sezione INFN di Pisa
  • Australian National University
  • Domaine Scientifique de la Doua
  • University of the West of Scotland

Abstract

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.

Details

Original languageEnglish
Article numberL39
JournalAstrophysical Journal Letters
Volume850
Issue number2
Publication statusPublished - 1 Dec 2017

Keywords

  • gravitational waves, methods: data analysis, stars: neutron