Probing Extreme (Astro)Physics with Neutron Stars

用中子星探索极限（天文）物理

• 批准号: RGPIN-2018-06624
• 负责人: VanKerkwijk, Marten
• 金额: $ 4.44万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714360
• 关键词: Probing; Extreme; Astro; Physics; Neutron

Neutron stars are the densest objects known to mankind, with a mass 1.4 times that of the Sun packed in a sphere with only 20 km diameter. They contain, as their name suggests, mostly neutrons, one of the two constituents of atomic nuclei. Indeed, one could envisage them as giant nuclei, although with a mean density about thrice that of atomic nuclei, and a core density that is higher still. We do not yet know how matter behaves at these densities, being unable to reach such densities in laboratories and not yet smart enough to calculate the behaviour theoretically. Part of my programme aims at finding out, by measuring properties of neutron stars. For instance, it may be that in the core the neutrons are packed so closely together that they dissolve, in their constituent quarks. If this were to happen, it would make matter more compressible, and a neutron star would be smaller for a given mass. My general aim is to test hypotheses such as these by measuring neutron star masses and radii, or combinations of the two, such as a the moment of inertia. A more specific aim is to find the heaviest neutron star. This tests how matter behaves at high densities because as one increases the mass of neutron star, there will be a limit beyond which gravity becomes too strong and the object collapses and becomes a black hole. This limit depends on the compressibility of matter: the more compressible, the lower the maximum mass. The current best limit, which I helped determine, is 2.0 solar masses. I also found a possibly more massive neutron star, with 2.4 solar masses, and one of my goals is to either confirm or refute that. What makes me particularly optimistic about measure accurate properties in the coming period, is a new technique we have been developing, which we dubbed “scintillometry.” Here, we make measurements of radio pulsars at extremely high angular resolution by using the interstellar medium as a giant interferometer - relying on the fact that the interstellar medium slightly deflects radio emission, which thus reaches us through different paths. With this technique, we should be able to measure the orbital motion of the pulsars on the sky, allowing us to infer the orientation of the orbits which is needed to measure the mass as well as, in princple, precise distances, which will help pinpoint merging super-massive black holes from their gravitational waves.

中子星是人类已知的最致密物体，质量是直径仅20 km的球体中的1.4倍。顾名思义，它们主要是中性的，这是原子核的两个构成之一。的确，人们可以将它们设想为巨大的核，尽管平均密度是原子核的平均密度，而核心密度却更高。 我们还不知道物质在这些密度下的行为如何，无法达到实验室中的密度，并且还不够聪明，无法计算行为理论。我的程序的一部分旨在通过测量中子星的性质来找出。例如，可能是在核心中，中子被挤在一起，以至于它们溶解在其组成夸克中。如果发生这种情况，这将使物质更加兼容，并且对于给定的质量而言，中子恒星将较小。我的总体目的是通过测量中子恒星质量和半径或两者的组合（例如惯性时刻）来检验诸如此类的假设。 一个更具体的目的是找到最重的中子星。这测试了物质在高密度下的行为方式，因为随着一个人的质量增加中子星的质量，将有一个极限，超出了重力变得太强大，物体崩溃并变成黑洞。此限制取决于物质的合理性：越兼容，最大质量越低。我帮助确定的当前最佳限制是2.0太阳能团块。我还发现可能具有2.4个太阳能的更大的中子恒星，我的目标之一就是确认或驳斥这一点。 使我对未来时期的测量准确属性的尤其优化的是我们一直在开发的一种新技术，我们将其称为“闪烁测定法”。在这里，我们通过使用星际介质作为巨型干涉仪，以极高的角度分辨率对无线电脉冲星进行测量 - 依靠以下事实：星际介质略微证明无线电发射，从而通过不同的路径到达我们。通过这种技术，我们应该可以测量脉冲星在天空上的轨道运动，从而使我们能够推断出测量质量的轨道的取向，以测量质量，以及在王子中，精确的距离，这将有助于确定从其重力波中合并超质量黑洞。