Short time domain coherent radio astronomy

这项建议是建立在甚长基线干涉测量（VLBI）的最新突破基础上的，以研究非常短时间尺度上不断变化的无线电宇宙。从几纳秒到几秒的短时间尺度上的研究很重要，因为天文学中许多最紧迫的问题都涉及难以研究的短暂现象。我们的团队最近创新了VLBI的新算法方法，现在允许我们在这些非常短的时间窗口内研究信号。 这些新工具的发展广泛地影响了致密天体天体物理学、引力波物理学和宇宙学。潜在的脉冲星和快速射电爆发（FRB）等离子体透镜的精确距离打开了精确定位纳赫兹引力波源的窗口，而FRB传播探测宇宙重子含量。这项研究可能会连接并实质性地影响以前联系薄弱的领域。 我们最近使用我们的新技术来描述黑寡妇脉冲星周围的极端等离子体透镜效应。虽然这颗脉冲星已经被研究了30年，但我们的团队是第一个开发出一个框架来解释其亮度的短暂变化，因为以前没有研究人员拥有分析这种短暂现象的工具，这种现象只持续几毫秒。这一发现的重要性在于，等离子体透镜效应就像一个放大镜，使我们能够以以前无法想象的精度研究深空现象。我们已经演示了如何利用这种效应来绘制距离6,500光年远的脉冲星的发射区域，分辨率达到1000光年。这一前所未有的壮举相当于从地球上测量火星上头发的宽度。 提高我们对等离子体透镜的理解，并利用它们来研究短时域现象将是这个计划的主要重点。短期目标包括： 1.了解星际透镜：等离子体透镜效应有可能彻底改变射电天文学，但其性质和几何形状尚不清楚。我们将使用VLBI测长术来绘制星际介质中的等离子体透镜。 2.使用等离子体透镜作为望远镜：我们还将使用VLBI测量来更好地探索使用散射屏作为星际等离子体透镜。 3.利用透镜效应研究FRB：FRB的性质是天体物理学中最令人困惑的谜团之一，也是研究的主要前沿。我们将使用我们的技术来实现FRB的系统空间定位。

This proposal builds on recent breakthroughs in Very Long Baseline Interferometry (VLBI) to study the changing radio universe on very short timescales. Research at short time scales, from a few nanoseconds to seconds, is important because many of the most pressing questions in astronomy concern difficult-to-study, fleeting phenomena. Our group recently innovated new algorithmic approaches to VLBI that now allow us to study signals in these very short time windows. The development of these new tools broadly impacts compact object astrophysics, gravitational wave physics, and cosmology. Potential pulsar and Fast Radio Burst (FRB) precision distances from plasma lensing open the window to the accurate localization of nanohertz gravitational wave sources, while FRB propagation probes the cosmic baryon content. This research is likely to connect and substantially impact previously weakly linked fields. We recently used our new technique to characterize an extreme plasma lensing effect around the Black Widow pulsar. Though this pulsar has been studied for 30 years, our group was the first to develop a framework to interpret its fleeting changes in brightness because no researcher previously had the tools to analyze this ephemeral phenomenon that lasts only a few milliseconds. The importance of this finding is that the plasma lensing effect functions as a magnifying glass that allows us to study deep space phenomena with previously unthinkable precision. We have demonstrated how we can use this effect to map the emission regions of a pulsar located 6,500 light years away with kilometre-level resolution. This unprecedented feat is equivalent to measuring the width of a hair on Mars from Earth. Improving our understanding of plasma lenses and their use to study short time domain phenomena will be the major focus of this program. Short-term objectives include: 1. Understanding Interstellar Lenses: Plasma lensing effects have the potential to revolutionize radio astronomy but their nature and geometry are unknown. We will use VLBI scintillometry to map plasma lenses in the interstellar medium. 2. Using Plasma Lenses as Telescopes: We will also use VLBI scintillometry to better explore the use of scattering screens as interstellar plasma lenses. 3. Using Lensing Effects to Study FRBs: The nature of FRBs is one of the most perplexing enigmas in astrophysics and a major front for research. We will use our technique to attain a systematic spatial localization of FRBs.