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密度最大的天体，其质量是太阳的 1.4 倍，聚集在直径仅为 20 公里的球体中，正如其名称所暗示的那样，中子主要是原子核的两种成分之一。 ，人们可以将它们想象为巨大的原子核，尽管其平均密度约为原子核的三倍，并且核心密度更高。 我们还不知道物质在这些密度下的行为，无法在实验室中达到这样的密度，而且还没有足够的智能来从理论上计算这种行为，例如，通过测量中子星的特性来找出答案。可能是在核心中，中子紧密地堆积在一起，以至于它们溶解在它们的组成夸克中。如果这种情况发生，物质将变得更可压缩，并且对于给定的中子星来说，中子星会更小。我的总体目标是通过测量中子星质量和半径或两者的组合（例如转动惯量）来检验此类假设。 更具体的目标是找到最重的中子星，这测试了物质在高密度下的行为，因为随着中子星质量的增加，重力会变得太强，物体会坍塌并成为黑洞。这个极限取决于物质的可压缩性：可压缩性越高，最大质量越低。我帮助确定的当前最佳极限是 2.0 个太阳质量，我还发现了一颗质量可能更大的中子星。 2.4 太阳质量，我的目标之一是证实或反驳这一点。 让我对未来测量精确特性特别乐观的是我们一直在开发的一项新技术，我们将其称为“闪烁测量法”。在这里，我们使用星际介质作为介质，以极高的角分辨率来测量射电脉冲星。巨型干涉仪 - 依靠星际介质稍微偏转无线电发射的事实，从而通过不同的路径到达我们，利用这种技术，我们应该能够测量天空中脉冲星的轨道运动，从而使我们能够测量脉冲星的轨道运动。推断出测量质量所需的轨道方向，以及原则上精确的距离，这将有助于从引力波中精确定位合并的超大质量黑洞。