GW170817及其电磁对应体的成功联合观测，标志着多信使天文学时代的开端。尽管对于GW170817的研究已经取得了巨大的成果，依然存在一些重大的问题没有完全解决。首先，并合产物究竟是一个黑洞还是一个长时标存在的中子星，目前尚未有定论。受限于现有引力波探测器在高频波段的灵敏度，无法从引力波是数据中找出支持或反对并合产物是长时标存活的中子星的证据。第二，伽马暴和余辉的观测都支持喷流在很大的张角内存在结构，但具体结构和物理参数还没有确定。 我的论文针对这两个问题进行讨论。首先，我们利用引力波和多波段电磁波的数据限制并合产物的性质。研究发现，部分较硬的中子星状态方程可以支撑中子星作为GW170817的并合中心产物存活，且需要中子星快速自转。当中子星的椭率达到10^?3时，其偶极磁场要小于～ 10^14G；当椭率小于～ 10^?4时，其偶极磁场的上限为～ 10^9 ?10^11G。这些结论只轻微依赖于中子星的状态方程。针对喷流的结构，我们提出如果喷流是结构化的，那么它会与周围介质作用产生外激波加速电子。中等相对论性的电子和近似各向同性并合新星的光子发生逆康普顿散射，将原本处于光学波段的光子 散射到X射线波段，并和并合新星同时达到峰值。以cocoon模型为例，如果并合产物是黑洞，利用现有的X射线探测器，此类信号的探测极限可以达到2Mpc；如果并合产物是磁星，探测极限可以达到200Mpc。

The joint detection of GW170817 and its electromagnetic (EM) counterparts marks the beginning of multi-messenger astronomy era. Although researches on GW170817 have made great breakthroughs,there are still some problems unsolved. One of the most important issues is whether a long-lived neutron star (NS) is formed during the merger, which has not been determined yet. Limited by the sensitivity of current gravitational wave detectors in high frequency, the case a long-lived NS as the merger remnant of GW170817 has not been excluded. Another problem is about the structure of jet. Some clues from gamma-ray burst and afterglow observations imply that there are structures induced by the jet core in a wide angle, but the distribution of physical parameters, such as the total energy and Lorentz factor, are still unclear. My paper discusses these two issues. First of all, we utilize multi-messenger data as much as possible to constrain the remnant’s properties. We ?nd if the NS equation of state (EOS) is sti? enough, a long-lived NS with rapid rotation could be formed as the merger remnant. When the ellipticity of NS reaches 10^?3, the dipole magnetic ?eld of NS should be constrained to the magnetarlevelof～10^14G. When ellipticity is smaller than 10^?4,the dipole magnetic field should be constrained to the level of ～ 10^9 ? 10^11G. Thses conclusions only slightly depend on the adoption of EOS. About the structure of jet, we propose that, if the jet is structured, it would interact with ambient medium and accelerate electrons through external shock in a wide angle. The near isotropic merger-nova photons could be scattered by the mild relativistic electrons to higher frequency through inverse Compton (IC) scattering process. The IC component peaks in X-ray band and is simultaneous with merger-nova emission. Taking cocoon model as an example, if the merger remnant is a BH, this signal could be detectable out to 2Mpc with current X-ray detectors; If the merger remnant is a magnetar, it could be detectable out to 200Mpc.