Collaborative research: WoU-MMA: Electrodynamics of Magnetospheric Interactions in Merging Neutron Star Binaries

2017年8月两颗中子星合并产生的引力波的探测是天体物理学的一个开创性事件。这两颗密度极高的前恒星的合并与一次短伽马射线暴(GRB)有关，这清楚地表明，合并为这种异常明亮的天体物理爆炸的短期类别提供了中心引擎。为了更好地理解中子星合并是如何产生短伽玛暴的，普渡大学和普林斯顿大学之间的一个研究合作将对合并进行理论和数值研究，特别关注合并可能产生的最早的电磁辐射，即中子星在主事件发生前相互螺旋而产生的前驱光。研究人员将模拟合并中子星的相互作用磁场，估计从可能的相干无线电波到X射线的功率、角度模式和宽带发射机制。该项目结合了高能天体物理和等离子体物理等广泛领域的研究。该项目解决了与引力波天文学、超强磁场的相互作用和亚原子粒子加速有关的多信使天体物理学中的各种问题。调查的结果也将有助于制定寻找可能的合并前体排放的策略。这项研究将包括两所大学的本科生参与，以及一个外展项目，其中包括正在研究的相互作用的动画电影。最有可能产生前驱辐射的场景是两颗中子星的电磁相互作用，通过在共同的中子星磁层内磁化等离子体的相对运动，产生感应电场。预计在第二颗中子星形成至少数百万年后，合并时间足够长，以至于在合并时，每个磁层可能都会自行消亡。当恒星螺旋进入时，由于相对轨道的运动，磁层可以被复活。该项目的主要目标是利用脉冲星磁层范例研究共同磁层的这种轨道复兴：由于磁化等离子体的运动和随后的真空击穿而产生感应电场。研究人员将考虑间隙的形成：沿磁力线具有高电场的区域，以及相互作用的中子星的轨道调制共同磁层中的重联层。中子星的自转和轨道运动可能会在共同的磁层内产生有利于发电机作用的条件，这将放大磁场。该团队还将研究通过产生等离子体脉泽来产生高亮度相干射电发射。这个项目推进了NSF宇宙大理想之窗的目标。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The detection of gravitational waves from the merger of two neutron stars in August 2017 was a seminal event for astrophysics. This amalgamation of two extremely dense former stars was associated with a short gamma-ray burst (GRB), making it clear that a merger provides the central engine of the short-duration class of this extraordinarily bright type of astrophysical explosion. In order to better understand how a neutron star merger produces a short GRB, a research collaboration between Purdue University and Princeton University will carry out theoretical and numerical investigations of the merger, with a particular focus on the earliest possible electromagnetic radiation from the merger, the precursor light produced as the neutron stars spiral toward each other before the main event. The researchers will perform simulations of the interacting magnetic fields of merging neutron stars, estimating the power, angular pattern and broadband emission mechanisms, from possible coherent radio waves to X-rays. The project combines research in broad areas of high energy astrophysics and plasma physics. The project addresses diverse problems in multi-messenger astrophysics related to gravitational wave astronomy, interaction of ultra-strong magnetic fields and acceleration of sub-atomic particles. The results of the investigation will also help formulate the strategies for searching for possible merger precursor emission. The research will include involvement of undergraduate students at both universities and an outreach program including animated movies of the interactions being studied.The most likely scenario to generate precursor emission is the electromagnetic interaction of two neutron stars via the creation of inductive electric fields through the relative motion of magnetized plasma within the common neutron star magnetosphere. It is expected that merger times, at least millions of years after the formation of the second neutron star, are sufficiently long that, at the time of the merger, each magnetosphere is likely to be dead on its own. As the stars spiral in, the magnetospheres can be revived due to the relative orbital motion. The main goal of the project is to study this orbital revival of the common magnetospheres by employing the pulsar magnetosphere paradigm: the generation of the inductive electric field due to the motion of magnetized plasma and ensuing vacuum breakdown. The researchers will consider the formation of gaps: regions with high electric field along magnetic field lines, and reconnection layers in the orbital-modulated common magnetosphere of interacting neutron stars. Spins and orbital motion of the neutron stars may generate conditions favorable for dynamo action within the common magnetosphere, which will amplify the magnetic field. The team will also study the generation of high brightness coherent radio emission via the production of a plasma maser. This project advances the goals of the NSF Windows on the Universe Big Idea.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.