During the final stages of a compact object merger, if at least one of the binary components is a magnetized neutron star (NS), then the orbital motion of the conducting companion induces a strong current along the magnetic field lines connecting the stars. This interaction also substantially expands the NS's open magnetic flux---and hence increases its wind luminosity---relative to that of an isolated pulsar. As the binary orbit shrinks due to gravitational radiation, the power and speed of this binary-induced inspiral wind may (depending on pair loading) secularly increase, leading to self-interaction and internal shocks in the outflow beyond the binary orbit. The magnetized forward shock can generate coherent radio emission via the synchrotron maser process, resulting in an observable radio precursor to binary NS merger. We perform 1D relativistic hydrodynamical simulations of shock interaction in the accelerating binary NS wind, assuming that the inspiral wind efficiently converts its Poynting flux into bulk kinetic energy prior to the shock radius. This is combined with the shock maser spectrum from particle-in-cell simulations, to generate synthetic radio light curves. The precursor burst with a fluence of $\sim1$ Jy$\cdot$ms at $\sim$GHz frequencies lasts $\sim 1-500$ ms following the merger for a source at $\sim3$ Gpc ($B_{\rm d}/10^{12}$ G)$^{8/9}$, where $B_{\rm d}$ is the dipole field strength of the more strongly-magnetized star. Given an outflow geometry concentrated along the binary equatorial, the signal may be preferentially observable for high-inclination systems, i.e. those least likely to produce a detectable gamma-ray burst.

中文翻译：

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加速相对论双星风中子星并合的冲击动力无线电前兆

在致密天体合并的最后阶段，如果双星中至少有一个是磁化中子星 (NS)，则导电伴星的轨道运动会沿着连接恒星的磁场线感应出强电流。这种相互作用也大大扩展了 NS 的开放磁通量——从而增加了它的风光度——相对于孤立脉冲星的光度。随着双星轨道因引力辐射而收缩，这种双星引起的吸气风的功率和速度可能（取决于对载荷）长期增加，导致双星轨道外流出的自相互作用和内部冲击。磁化的前向激波可以通过同步加速器脉泽过程产生相干无线电发射，从而产生可观测的双 NS 合并的无线电前兆。我们在加速的二元 NS 风中执行激波相互作用的一维相对论流体动力学模拟，假设吸入风在激波半径之前有效地将其坡印廷通量转换为体动能。这与来自细胞内粒子模拟的激波脉泽光谱相结合，以生成合成射电光曲线。在 $\sim3$ Gpc ($B_{\ rm d}/10^{12}$ G)$^{8/9}$，其中 $B_{\rm d}$ 是强磁化恒星的偶极场强。给定沿双赤道集中的流出几何形状，对于高倾角系统，即那些最不可能产生可探测伽马射线爆发的系统，信号可能优先被观测到。