We explore magnetic-field amplification due to the Kelvin-Helmholtz instability during binary neutron star mergers. By performing high-resolution general relativistic magnetohydrodynamics simulations with a resolution of 17.5 m for 4–5 ms after the onset of the merger on the Japanese supercomputer “K”, we find that an initial magnetic field of moderate maximum strength ${10}^{13}\mathrm{G}$ is amplified at least by a factor of $\approx {10}^3$. We also explore the saturation of the magnetic-field energy and our result shows that it is likely to be $\gtrsim 4\times {10}^{50}\mathrm{erg}$, which is $\gtrsim 0.1\%$ of the bulk kinetic energy of the merging binary neutron stars.

• Received 30 September 2015

DOI:https://doi.org/10.1103/PhysRevD.92.124034