Self-Consistent Pulsar Magnetosphere Models:Macroscopic and Kinetic Models in the FERMI Era

“中子星”将太阳的质量压缩成一个曼哈顿岛大小的体积。由于密度如此之高，单个原子核相互挤压，溶解成中子。在20世纪60年代，射电天文学家发现了脉动射电源。科学家们很快意识到这些“脉冲星”是快速旋转的中子星。它们的自转周期从几秒到千分之几秒不等。比地球磁场强一万亿倍以上的磁场被“冻结”在中子星中，导致脉冲星的射电发射。近半个世纪以来，产生这些无线电信号的实际机制一直是个谜。在过去的十年里，使用费米宇宙飞船的观测发现了100多颗发射脉冲伽马射线和脉冲无线电信号的脉冲星。研究人员建议计算脉冲星周围空间中电子和正电子（带正电的电子）行为的详细三维数值模型。他们的研究将试图建立这些所谓的“脉冲星磁层”的第一个自洽模型。这项研究的目的是使科学家能够预测脉冲星发射的全光谱。这将使他们能够通过观察来检验理论。如果成功，这些结果将从这项工作中提供非常强大的智力影响。更广泛的影响来自于研究人员在几个层面上促进STEM教育的活动，以及创新地使用3D打印来制造脉冲星磁层的3D模型。如上所述，脉冲星是快速旋转的中子星，具有极强的磁场。天体物理学家很快确定，这种“冻结”成快速旋转恒星的强磁场，将以非常高的速率辐射电磁能量。在过去的十年里，费米伽玛射线太空望远镜已经探测到来自100多颗脉冲星的伽玛辐射，研究人员的初步工作已经证明，在生成伽玛射线光曲线方面取得了显著的成功，可以与这些观测结果进行比较。该研究将采用几种最新的计算机代码，通过脉冲星磁层的三维数值模拟来解决脉冲星发射机制的复杂问题。该项目将结合使用细胞内粒子（PIC）方法计算等离子体粒子的微观行为和使用磁流体动力学（MHD）模拟计算大尺度等离子体行为，努力开发完全自洽的三维模型。该项目的智力影响来自于这样一个事实，即如果它成功了，这项工作将构成我们对脉冲星理解的有价值的一步。这项工作的更广泛影响来自于pi在几个层面上促进STEM教育的活动，以及创新地使用3D打印来制造脉冲星磁层的3D模型。

"Neutron stars" pack the mass of our Sun into a volume the size of Manhattan Island. Because the density is so high, individual atomic nuclei crowd against each other and dissolve into neutrons. In the 1960s, radio astronomers discovered pulsating radio sources. Scientists soon realized that these "pulsars" are rapidly rotating neutron stars. Their rotation periods range from a few seconds down to several thousandths of a second. Magnetic fields more than a trillion times stronger than Earth's magnetic field are "frozen" into the neutron star, causing the pulsar radio emission. The actual mechanism responsible for generating these radio signals has remained a mystery for nearly half a century. Within the past decade, observations using the Fermi spacecraft have revealed more than 100 pulsars that emit pulsed gamma rays as well as pulsed radio signals. The Investigators propose to compute detailed, three-dimensional numerical models for the behavior of electrons and positrons (positively charged electrons) in the space surrounding a pulsar. Their research will attempt to produce the first self-consistent models of these so-called "pulsar magnetospheres." The goal of this research is to enable scientists to predict the full spectrum of emission from a pulsar. This will allow them to test the theory against observations. If successful, these results will provide very strong Intellectual Impact from this work. The Broader Impacts derive from the Investigators' activities to promote STEM education at several levels and from an innovative use of 3D printing to fabricate 3D models of pulsar magnetospheres.As noted above, pulsars are rapidly rotating neutron stars, with enormously strong magnetic fields. Astrophysicists quickly determined that such strong fields, "frozen" into rapidly rotating stars, would radiate electromagnetic energy at very high rates. Observations from the Fermi Gamma-Ray Space Telescope within the past decade have now detected gamma radiation from more than 100 pulsars, and preliminary work by the Investigators has demonstrated remarkable success in generating gamma-ray lightcurves that can be compared with these observations. The proposed research will employ several up-to-date computer codes to attack the complicated problem of the pulsar emission mechanism through three-dimensional numerical simulations of pulsar magnetospheres. The project will combine computations of the microscopic behavior of the plasma particles using particle-in-cell (PIC) methods with computations of the large-scale plasma behavior using magnetohydrodynamic (MHD) simulations in an effort to develop fully self-consistent three-dimensional models. The Intellectual Impact of the project results from the fact that, if it is successful, this work will constitute a valuable step forward in our understanding of pulsars. The Broader Impacts of the work derive from the PIs' activities to promote STEM education at several levels and from innovative use of 3D printing to fabricate 3D models of pulsar magnetospheres.