ausblenden:
Schlagwörter:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Zusammenfassung:
Numerical-relativity simulations for seconds-long black hole-neutron star
mergers are performed to obtain a self-consistent picture starting from the
inspiral and the merger throughout the post-merger stages for a variety of
setups. Irrespective of the initial and computational setups, we find
qualitatively universal evolution processes: The dynamical mass ejection takes
place together with a massive accretion disk formation after the neutron star
is tidally disrupted; Subsequently, the magnetic field in the accretion disk is
amplified by the magnetic winding, Kelvin-Helmholtz instability, and
magnetorotational instability, which establish a turbulent state inducing the
dynamo and angular momentum transport; The post-merger mass ejection by the
effective viscous effects stemming from the magnetohydrodynamics turbulence
sets in at $\sim300$-$500$ ms after the merger and continues for several
hundred ms; A magnetosphere near the black-hole spin axis is developed and the
collimated strong Poynting flux is generated with its lifetime of $\sim0.5$-$2$
s. The model of no equatorial-plane symmetry shows the reverse of the
magnetic-field polarity in the magnetosphere, which is caused by the dynamo
associated with the magnetorotational instability in the accretion disk. The
model with initially toroidal fields shows the tilt of the disk and
magnetosphere in the late post-merger stage because of the anisotropic
post-merger mass ejection. These effects could terminate the strong
Poynting-luminosity stage within the timescale of $\sim0.5$-$2$ s.
