Shock-powered radio precursors of neutron star mergers from accelerating relativistic binary winds
Shock-powered radio precursors of neutron star mergers from accelerating relativistic binary winds
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DOI：
10.1093/mnras/staa3794
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发表时间：
2020-10
影响因子：
4.8
通讯作者：
N. Sridhar;J. Zrake;B. Metzger;L. Sironi;D. Giannios
中科院分区：
文献类型：
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作者：
N. Sridhar;J. Zrake;B. Metzger;L. Sironi;D. Giannios
在紧凑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星（NS），那么相对于孤立的脉冲星，它的轨道运动会大大扩大NS的开放磁通量，从而增加其风光度。由于引力辐射，双星轨道收缩，这种双星诱导的内旋风的功率和速度可能（取决于对负载）长期增加，导致自相互作用和内部冲击的流出超出双星轨道。磁化的前向激波可以通过同步脉泽过程产生相干射电辐射，从而产生可观测到的双星NS合并的射电前兆。我们进行一维相对论流体动力学模拟激波相互作用的加速二进制NS风，假设螺旋风有效地将其坡印亭通量转化为散装动能之前的激波半径。这与粒子模拟的激波脉泽光谱相结合，产生合成的射电光变曲线。对于一个强度为103 Gpc（Bd/1012 G）8/9的源，在合并后，在100 GHz频率下通量为101 Jy·ms的前兆爆发持续101 -500 ms，其中Bd是较强磁化星星的偶极场强。给定一个流出的几何形状集中沿着的双赤道平面，信号可能是优先观察到的高倾角系统，也就是说，那些最不可能产生可检测的伽马射线爆发。
During the final stages of a compact object merger, if at least one of the binary components is a magnetized neutron star (NS), then its orbital motion 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 ∼1 Jy·ms at ∼GHz frequencies lasts ∼1–500 ms following the merger for a source at ∼3 Gpc (Bd/1012 G)8/9, where Bd is the dipole field strength of the more strongly magnetized star. Given an outflow geometry concentrated along the binary equatorial plane, the signal may be preferentially observable for high-inclination systems, that is, those least likely to produce a detectable gamma-ray burst.