Astrophysics of Neutron Stars and Supernova Remnants

提议的工作是基础研究，其目标是(A)利用中子星了解物质的基本性质，以及(B)利用超新星遗迹了解物质的生命周期。中子星是一颗大质量恒星爆炸时产生的密度极高的物体。它的密度比原子核还要高（是水密度的100万亿倍），比宇宙中任何地方都要高。它的质量和太阳差不多（是地球质量的100万倍）。超新星遗迹是由恒星（超新星）爆炸加热的热（百万度）气体。这些气体以每小时100万英里的速度射向恒星之间的空间。对于中子星，这项工作将测量质量和半径值。质量和半径取决于核物质的密度和压力，因此这些测量是至关重要的，将用于理解核物质的物理特性（拉蒂默和普拉卡什，2016，物理报告，621,127）。我的工作采用两种方法。1)对x射线双星系统的观测将建模。我对大力神X-1进行了数十年的研究，得出了系统的几何形状和特性，以及中子星的质量半径比。下一步是测量系统倾角，这将得到中子星的质量和半径。2)将模拟毫秒脉冲星的x射线脉冲形状，以获得质量和半径值：这将与国际专家合作完成。对于超新星残余物（SNRs），这项工作将确定超新星（SN）爆炸能量、年龄、出生率和爆炸前周围气体的性质。这是通过i)确定到信噪比的距离和ii)模拟多波长的信噪比观测来实现的。确定距离是一个技术问题，我是与北京天文台田博士合作的世界级专家。建立信噪比模型是我的另一个关注点。高温气体是信噪比的主要组成部分，释放出x射线。我用x射线发射模型来告诉我们信噪比的特性。与SN相比，snr的寿命更长（约5万年，而SN的寿命为1个月），因此snr可以很好地研究SN爆炸。有了足够数量的信噪比，就可以确定SN爆炸的一般性质。爆炸冲击波决定了银河系和地球上的大多数元素是如何形成的。爆炸的能量决定了银河系中气体的运动，以及这些气体如何形成新的恒星。研究信噪比是了解超新星及其对银河系性质影响的最佳方式，包括新恒星的形成方式，以及恒星之间气体的性质和元素组成。对加拿大的好处包括提高加拿大在基础科学方面的声誉，并培养研究生成为下一代问题解决者。对于天体物理学来说，对中子星和超新星遗迹的理解提高了我们对大质量恒星的理解，它们对宇宙的各个尺度都有影响。

The proposed work is basic research with the goals of (A) learning about the fundamental nature of matter, using neutron stars, and of (B) understanding the life-cycle of matter, using supernova remnants. A neutron star is an extremely dense object created when a massive star explodes. Its density is higher than an atomic nucleus (100 trillion times the density of water), higher than anywhere else in the universe. Its mass is similar to that of our sun (1 million times as massive as the Earth). A supernova remnant is the hot (million degree) gas heated by the explosion of a star (a supernova). The gas shoots out into the space between the stars at about a million miles per hour. For neutron stars, this work will measure mass and radius values. The mass and radius depend on the density and pressure of nuclear matter, thus these measurements are crucial and will be used to understand the physics of nuclear matter (Lattimer and Prakash, 2016, Physics Reports, 621, 127). My work takes two approaches. 1) Observations of X-ray binary systems will be modeled. My multi-decade study of Hercules X-1 has yielded system geometry and properties, and mass-to-radius ratio for the neutron star. The next step is to measure system inclination, which will yield mass and radius for the neutron star. 2) X-ray pulse shapes of millisecond pulsars will be modeled to obtain mass and radius values: this will be done in collaboration with international experts.For supernova remnants (SNRs), this work will determine supernova (SN) explosion energies, ages, birthrates and the nature of the surrounding gas before the explosion. This is accomplished by i) determining distances to SNRs, and ii) modelling multi-wavelength observations of SNRs. Determining distances is a technical problem for which I am a world expert in collaboration with Dr. Tian of Beijing Astronomical Observatory. Modelling SNR is my other focus. The hot gas, which is the main part of a SNR, emits X-rays. I use models of X-ray emission to tell us the properties of SNR. SNRs are long-lived compared to SN (about 50,000 yr compared to 1 month), so SN explosions can be well studied using SNRs. With a sufficient number of SNRs, general properties of SN explosions will be determined. The explosion shock determines how most elements in our Galaxy, and on Earth, are created. The explosion energy determines the motions of the gas in our Galaxy, and how this gas can form new stars. Studying SNRs is the best way to learn about SN and their effects on the nature of our Galaxy, including how new stars form, and the properties and elemental composition of the gas between the stars.The benefits to Canada include enhancement of Canada's reputation in fundamental science, and training graduate students to be the next-generation problem solvers. For astrophysics, the understanding neutron stars and supernova remnants improves our understanding of massive stars, which have effects on all scales in our universe.