Activity of Strongly Magnetized Neutron Stars

被称为中子星（NS）的密度极高的恒星残骸并不是安静的物体。众所周知，它们的地壳会发生地震，从而产生明亮的辐射。就像地震使地质学家能够研究地球内部一样，中子星地震使天文学家能够探测恒星的内部，这是高能天体物理学中最重要的问题之一。哥伦比亚大学的一个研究小组将使用计算机模拟来模拟中子星地震及其与中子星磁层的相互作用，以更好地理解观测现象，如中子星时间故障、高磁化的中子星爆发、巨大的中子星耀斑、中子星合并的电磁前体，甚至可能解决产生神秘的快速射电暴（frb）的问题，这可能是由磁星引起的。更一般地说，理论天体物理学通过促进对宇宙的认识和教育产生了更广泛的影响。拟议的研究结果将在会议上传播，并作为哥伦比亚大学高能天体物理学课程的一部分教授。这项研究将包括对研究生和本科生的培训。地震磁层发射的第一性原理模拟是新颖的，将大大推动该领域的发展。该研究小组开发了一种新的代码，可以跟踪地震激发的剪切波在整个地壳、液体地核和磁层中的传播。磁层活动将使用该小组开发的先进等离子体代码进行检查，该代码是为中子星周围电子-正电子放电的全球动力学模拟而设计的。该提案包括两个部分。(1)磁层对地壳地震响应的第一性原理模拟及产生的辐射计算。模拟方法将用于研究两种现象：(a)最近发现的船帆座脉冲星在自旋故障期间窒息。这次观测很可能见证了一场强大的星震。(b)磁星地震发射的x射线暴，这是一个长期存在的难题。(2)建立了一个年轻的、超活跃的磁星演化模型。这些假设的物体似乎是宇宙快速射电暴的引擎。该项目的重点是超活动的驱动因素——中子星核心的双极扩散——及其对磁层的影响，导致磁耀斑和在磁星风中发射冲击波。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Extremely dense stellar remnants, known as neutron stars (NS), are not quiet objects. They are known to have quakes in their crusts, which can produce bright bursts of radiation. Like earthquakes allow geologists to study the interior of the Earth, neutron star quakes allow astronomers to probe the star’s interior, one of the most important questions in high-energy astrophysics. A research group at Columbia University will use computer simulations to model NS quakes and their interactions with the NS magnetosphere, to better understand observational phenomena such as NS timing glitches, bursts from highly magnetized NS called magnetars, giant NS flares, electromagnetic precursors of neutron star mergers, and perhaps even solve the production of mysterious fast radio bursts (FRBs), which may arise from magnetars. More generally, theoretical astrophysics has a broader impact through promoting knowledge about our universe and through education. The results of the proposed research will be disseminated at conferences and taught as part of high-energy astrophysics course at Columbia University. The research will involve training of graduate and undergraduate students. First-principle simulations of magnetospheric emission from a quake are novel and will significantly advance the field. The research group has developed a new code that follows the spreading of shear waves excited by a quake into the entire crust, the liquid core, and the magnetosphere. The magnetospheric activity will be examined using an advanced plasma code developed by the group and designed for global kinetic simulations of electron-positron discharge around neutron stars. The proposal has two parts. (1) First-principle simulations of the magnetospheric response to crustal quakes and calculation of the produced radiation. The simulation method will be used to investigate two phenomena: (a) The recently discovered choking of the Vela pulsar during a spin glitch. This observation likely witnessed a powerful starquake. (b) The emission of X-ray bursts by magnetar quakes, a long-standing puzzle. (2) Development of an evolutionary model of young, hyper-active magnetars. These hypothetical objects are plausible engines of cosmological FRBs. The project focuses on the driver of hyper-activity --- ambipolar diffusion in the neutron star core --- and its effect on the magnetosphere, leading to magnetic flares and launching blast waves in the magnetar wind.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.