双中子星并合的中微子信号

2017年8月17日，LIGO/Virgo首次探测到了双中子星并合事件的引力波信号，随后多波段的跟进观测获得了GW170817事件的多波段“全息”图像并确认源头在40 Mpc外的NGC4993星系，但颇为遗憾的是(尽管与理论预期符合)当时全球运行中的中微子探测器都没有探测到与GW170817相关联的中微子。普遍认为，热中微子在双星引力潮汐撕裂绕行阶段就会产生，在并合事件后的十几毫秒内达到峰值；若并合中心产物为伽马射线暴或者稳定的磁星，还会在并合的即刻至数天内产生超高能中微子。因此，中微子信号不仅可以辅助研究并合后的产物环境，还可以在天文尺度上研究中微子的基本性质和寻找粒子物理标准模型之外的新物理。即使只探测到一个热中微子事件，也可以获得热中微子的能谱标度信息和诊断并合后十几毫秒内星体本身和周围环境的物理参数。另外，因为引力波以光速传播，通过热中微子信号相对引力波信号的时延，可限制中微子的绝对质量。若探测到延迟的高能中微子信号，除了可以清楚地证明双中子星并合的中心产物是磁星，还可以研究并合产物附近的磁场环境和宇宙射线加速机制。

Neutrino emission from binary neutron star mergers

Both thermal and non-thermal neutrinos are expected to produce in binary neutron star (BNS) merger events. The thermal neutrino production starts from the tidal disruption during the inspiral phase and peaks at tens of milliseconds after the merging event. If the merger remnant ends up as a short gamma ray burst or a stable magnetar, substantial particle acceleration can occur in the corresponding relativistic shock waves or pulsar wind nebula, resulting in prompt to delayed emissions of (ultra) high energy neutrinos. Therefore, observation of neutrinos from BNS merger events can not only help to dissect the instantaneous and remnant merger environments, decipher the cosmic ray acceleration mechanism, but also can help to study the fundamental properties of neutrinos and search for new physics beyond the Standard Model of particle physics over astronomical baselines.