Extreme Physics with Pulsars and Radio Transients

紧凑的恒星物体，如中子星，为探索广泛的基本物理问题提供了机会。许多中子星发射出灯塔一样的射电波束，每旋转一次就可能击中地球一次，因此我们给这颗恒星贴上脉冲星的标签。旋转最快的脉冲星每秒旋转数百次，在短时间尺度上的稳定性可以与原子钟相媲美。这些毫秒脉冲星分布在天空中，可以用来直接探测经过地球附近的引力波。据预测，这些引力波的主要来源是最近经历合并的星系中心的超大质量黑洞对，与激光干涉引力波天文台（LIGO）最近探测到的恒星质量黑洞高度互补。这里提出的脉冲星定时阵列研究将提高北美纳赫兹引力波天文台（nanogravity）的有效性，通过改进当前的数据减少方法，并引入全新的数据，这些数据将解决由于星际介质变化而引起的系统学问题。这些数据将来自加拿大氢强度测绘实验（CHIME）望远镜，该望远镜目前正在不列颠哥伦比亚省彭迪克顿建造，在完成最初的宇宙学任务的同时，CHIME将提供北纳米重力脉冲星的日常数据，使我们能够比目前更详细地模拟星际介质的变化，并对高频纳米重力数据进行修正。这个项目将加快nanogravity探测引力波的时间。CHIME还将提供许多其他有趣脉冲星的密集数据集，包括相对论双星，这是该研究小组的另一个长期兴趣。******CHIME在处理仍然神秘的快速射电暴（frb）方面更有希望。这些是射电发射的单个尖峰，几乎可以肯定起源于银河系外，可以用现存的一些最大的射电望远镜观测到。其中一种来源现在被认为是重复的，但目前尚不清楚是否有两类来源。导致爆发的原因仍然未知——事实上，目前发表的想法比爆发还多——但推断出的亮度和短时间尺度表明，可能涉及中子星等致密物体。利用CHIME上的第二台专用仪器，我们预计每天可以探测到几十个快速射电暴；大大改进的统计数据将限制模型，并可能有助于更好地定位爆发，以识别宿主星系。

Compact stellar objects such as neutron stars offer the opportunity to probe a wide range of fundamental physics problems. Many neutron stars emit lighthouse-like radio beams, which may hit the Earth once per rotation and cause us to label the star a pulsar. The fastest-spinning pulsars rotate several hundred times per second and can rival the stability of atomic clocks on short timescales. An array of these millisecond pulsars, spread across the sky, can be used to make a direct detection of gravitational waves passing near the Earth. The main sources of these gravitational waves is predicted to be pairs of supermassive black holes as the centres of galaxies that have recently undergone mergers, highly complementary to the stellar-mass black holes recently detected by the Laser Interferometric Gravitational-wave Observatory (LIGO). The pulsar timing array research proposed here will enhance the effectiveness of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), by improving the current data-reduction methods and by bringing in entirely new data which will address systematics due to variations in the interstellar medium. These data will come from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope under construction in Penticton, B.C. Simultaneously with its original cosmology mission, CHIME will provide daily data on the Northen NANOGrav pulsars, allowing us to model the variations in the interstellar medium in more detail than currently possible and providing corrections to the higher-frequency NANOGrav data. This project will accelerate the timeline for NANOGrav to make a detection of gravitational waves. CHIME will also provide dense data sets on numerous other interesting pulsars, including relativistic binaries, which are another long-term interest of this research group.******CHIME holds still more promise, for tackling the still-mysterious Fast Radio Bursts (FRBs). These are single spikes of radio emission, almost certainly extragalactic in origin, seen with some of the largest radio telescopes in existence. One of these sources has now been seen to repeat, but it is unclear at present whether there are two classes of source. What causes the bursts is still unknown-- in fact there are more published ideas than bursts at present -- but the inferred brightness and short timescale indicate that the involvement of a compact object such as a neutron star is likely. With a dedicated second instrument on CHIME, we expect to detect several tens of FRBs per day; the vastly improved statistics will constrain models and may help to localize the bursts well enough to identify host galaxies.