Two neutron stars merge somewhere in the Universe approximately every 10 to 100 s, creating violent explosions potentially observable in gravitational waves and across the electromagnetic spectrum. The transformative coincident gravitational-wave and electromagnetic observations of the binary neutron star merger GW170817 gave invaluable insights into these cataclysmic collisions, probing bulk nuclear matter at supranuclear densities, the jet structure of gamma-ray bursts, the speed of gravity, and the cosmological evolution of the local Universe, among other things. Despite the wealth of information, it is still unclear when the remnant of GW170817 collapsed to form a black hole. Evidence from other short gamma-ray bursts indicates a large fraction of mergers may form long-lived neutron stars. We review what is known observationally and theoretically about binary neutron star post-merger remnants. From a theoretical perspective, we review our understanding of the evolution of short- and long-lived merger remnants, including fluid, magnetic-field, and temperature evolution. These considerations impact prospects of detection of gravitational waves from either short- or long-lived neutron star remnants which potentially allows for new probes into the hot nuclear equation of state in conditions inaccessible in terrestrial experiments. We also review prospects for determining post-merger physics from current and future electromagnetic observations, including kilonovae and late-time X-ray and radio afterglow observations.

大约每 10 到 100 秒，两颗中子星在宇宙中的某个地方合并，产生可能在引力波和整个电磁波谱中观察到的剧烈爆炸。对双中子星并合 GW170817 的变革性重合引力波和电磁观测为这些灾难性碰撞提供了宝贵的见解，探测超核密度的大量核物质、伽马射线爆发的喷射结构、重力速度和宇宙演化的本地宇宙，除此之外。尽管有丰富的信息，但仍不清楚 GW170817 的残骸何时坍塌形成黑洞。来自其他短伽马射线爆发的证据表明，很大一部分合并可能形成长寿的中子星。我们回顾了关于双中子星合并后残余物的观察和理论知识。从理论的角度，我们回顾了我们对短期和长期合并残余演化的理解，包括流体、磁场和温度演化。这些考虑影响了从短寿命或长寿命中子星残余物中探测引力波的前景，这可能允许在陆地实验无法达到的条件下对热核状态方程进行新的探测。我们还回顾了从当前和未来电磁观测确定合并后物理学的前景，包括千新星和后期 X 射线和无线电余辉观测。我们回顾了我们对短期和长期合并残余演化的理解，包括流体、磁场和温度演化。这些考虑影响了从短寿命或长寿命中子星残余物中探测引力波的前景，这可能允许在陆地实验无法达到的条件下对热核状态方程进行新的探测。我们还回顾了从当前和未来电磁观测确定合并后物理学的前景，包括千新星和后期 X 射线和无线电余辉观测。我们回顾了我们对短期和长期合并残余演化的理解，包括流体、磁场和温度演化。这些考虑影响了从短寿命或长寿命中子星残余物中探测引力波的前景，这可能允许在陆地实验无法达到的条件下对热核状态方程进行新的探测。我们还回顾了从当前和未来电磁观测确定合并后物理学的前景，包括千新星和后期 X 射线和无线电余辉观测。这些考虑影响了从短寿命或长寿命中子星残余物中探测引力波的前景，这可能允许在陆地实验无法达到的条件下对热核状态方程进行新的探测。我们还回顾了从当前和未来电磁观测确定合并后物理学的前景，包括千新星和后期 X 射线和无线电余辉观测。这些考虑影响了从短寿命或长寿命中子星残余物中探测引力波的前景，这可能允许在陆地实验无法达到的条件下对热核状态方程进行新的探测。我们还回顾了从当前和未来电磁观测确定合并后物理学的前景，包括千新星和后期 X 射线和无线电余辉观测。