Zachariah B. Etienne, Yuk Tung Liu, Vasileios Paschalidis, Stuart L. Shapiro
As a neutron star (NS) is tidally disrupted by a black hole (BH) companion at
the end of a BH-NS binary inspiral, its magnetic fields will be stretched and
amplified. If sufficiently strong, these magnetic fields may impact the
gravitational waveforms, merger evolution and mass of the remnant disk.
Formation of highly-collimated magnetic field lines in the disk+spinning BH
remnant may launch relativistic jets, providing the engine for a short-hard
GRB. We analyze this scenario through fully general relativistic,
magnetohydrodynamic (GRMHD) BHNS simulations from inspiral through merger and
disk formation. Different initial magnetic field configurations and strengths
are chosen for the NS interior for both nonspinning and moderately spinning
(a/M=0.75) BHs aligned with the orbital angular momentum. Only strong interior
(Bmax~10^17 G) initial magnetic fields in the NS significantly influence merger
dynamics, enhancing the remnant disk mass by 100% and 40% in the nonspinning
and spinning BH cases, respectively. However, detecting the imprint of even a
strong magnetic field may be challenging for Advanced LIGO. Though there is no
evidence of mass outflows or magnetic field collimation during the preliminary
simulations we have performed, higher resolution, coupled with longer disk
evolutions and different initial magnetic field configurations, may be required
to definitively assess the possibility of BHNS binaries as short-hard GRB
progenitors.
View original:
http://arxiv.org/abs/1112.0568
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