http://arxiv.org/abs/1510.03432
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 post-merger 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 timescale of $\sim 10$ ms, with the $m=1$ azimuthal density multipole mode dominating over higher modes. The instability also leaves a characteristic imprint on the post-merger gravitational wave signal that could be detectable if the instability persists in long-lived remnants.
V. Paschalidis, W. East, F. Pretorius, et. al.
Wed, 14 Oct 15
21/66
Comments: 6 pages, 3 figures, submitted for publication
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