Neutron stars: probing physics at the extreme

我的研究贯穿了一个总的主题：我们对天体物理现象和基础物理的理解是如何联系在一起的。中子星提供了一个实验室，以最大限度地测试我们对自然的认识。中子星的磁场、密度和压强超过地球上产生的磁场、密度和压力的10亿倍以上。中子星提供了一个独特的机会来推断和验证我们关于物质、能量及其相互作用的理论。我最近和未来的研究计划集中在对这些物体和相关物体的理论和观测理解上。中子星是我们在宇宙中可以直接观察到的最密集的物体-黑洞的中心奇点密度更高，但它隐藏在事件视界后面，无法观察到。在一颗大质量恒星的生命结束时，它的核心由大约一到两个太阳质量组成，塌缩成一个半径约10公里的球体，中子星的平均密度为1e15g/cc，大于原子核的密度。在崩塌过程中，地核的磁场通常会增强到1e12G，大约10%的时间会增强到1e15G(形成磁星--这是我的团队最近的结果)。这些天体密度极高的核心中的物质相超出了我们目前的知识，探测它是研究中子星的目标之一。在核心上方是一层(约1公里厚)亚核密度的物质。这种材料的物相是已知的，但它的许多性质还没有确定。这种密度较低的物质调节着能量从核心到表面的转移，产生了许多中子星的现象学。

A general theme threads my research: how is our understanding of astrophysical phenomena and fundamental physics connected. Neutron stars provide a laboratory to test our knowledge of nature at the extreme. The magnetic fields, densities and pressures of neutron stars exceed those produced on Earth more than a billion-fold. Neutron stars provide a unique opportunity to extrapolate and verify our theories of matter, energy and their interaction. My recent and future research program focusses on the theoretical and observational understanding of these and related objects. Neutron stars are the densest objects that we can directly observe in the universe --- the central singularity of a black hole is denser but it is hidden behind an event horizon and unobservable. At the end of a massive star's life, its core comprising of about one to two solar masses collapses to a sphere about ten kilometers in radius, the neutron star with a mean density of 1e15 g/cc, greater than the density of atomic nuclei. During the collapse the magnetic field of the core intensifies reaching 1e12 G typically and up to 1e15 G about ten percent of the time (forming a magnetar - this fraction is a recent result from my group). The phase of matter within the extremely dense cores of these objects lies beyond our current knowledge, and probing it is one goal of studying neutron stars. Above the core lies a crust (about 1 km thick) of material at subnuclear density. The phase of this material is known, but many of its properties have not yet been determined. This lower density material regulates the transfer of energy from the core to the surface, generating much of the phenomenology of neutron stars.