One-arm spiral instability in hypermassive neutron stars formed by dynamical-capture binary neutron star mergers

Vasileios Paschalidis, William E. East, Frans Pretorius, Stuart L. Shapiro

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

Using general-relativistic hydrodynamical simulations, we show that merging binary neutron stars can form hypermassive neutrons stars that undergo the one-arm spiral instability. We study the particular case of a dynamical capture merger where the stars have a small spin, as may arise in globular clusters, and focus on an equal-mass scenario where the spins are aligned with the orbital angular momentum. We find that this instability develops when postmerger fluid vortices lead to the generation of a toroidal remnant - a configuration whose maximum density occurs in a ring around the center-of-mass - with high vorticity along its rotation axis. The instability quickly saturates on a time scale of ∼10 ms, with the m=1 azimuthal density multipole mode dominating over higher modes. The instability also leaves a characteristic imprint on the postmerger gravitational wave signal that could be detectable if the instability persists in long-lived remnants.

Original languageEnglish (US)
Article number121502
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume92
Issue number12
DOIs
StatePublished - Dec 30 2015

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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