10,514 research outputs found
Persistent spin current and entanglement in the anisotropic spin ring i
We investigate the ground state persistent spin current and the pair
entanglement in one-dimensional antiferromagnetic anisotropic Heisenberg ring
with twisted boundary conditions. Solving Bethe ansatz equations numerically,
we calculate the dependence of the ground state energy on the total magnetic
flux through the ring, and the resulting persistent current. Motivated by
recent development of quantum entanglement theory, we study the properties of
the ground state concurrence under the influence of the flux through the
anisotropic Heisenberg ring. We also include an external magnetic field and
discuss the properties of the persistent current and the concurrence in the
presence of the magnetic field.Comment: 5 pages, 8 figure
The Allowed Parameter Space of a Long-lived Neutron Star as the Merger Remnant of GW170817
Due to the limited sensitivity of the current gravitational wave (GW) detectors, the central remnant of the binary neutron star (NS) merger associated with GW170817 remains an open question. In view of the relatively large total mass, it is generally proposed that the merger of GW170817 would lead to a short-lived hypermassive NS or directly produce a black hole (BH). There is no clear evidence to support or rule out a long-lived NS as the merger remnant. Here, we utilize the GW and electromagnetic (EM) signals to comprehensively investigate the parameter space that allows a long-lived NS to survive as the merger remnant of GW170817. We find that for some stiff equations of state, the merger of GW170817 could, in principle, lead to a massive NS, which has a millisecond spin period. The post-merger GW signal could hardly constrain the ellipticity of the NS. If the ellipticity reaches 10−3, in order to be compatible with the multi-band EM observations, the dipole magnetic field of the NS (B p ) is constrained to the magnetar level of ~1014 G. If the ellipticity is smaller than 10−4, B p is constrained to the level of ~109–1011 G. These conclusions weakly depend on the adoption of the NS equation of state
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