利用快速射电暴纳米透镜探测河外系外行星
Detecting Extragalactic Exoplanets With Fast Radio Burst Nanolensing
- Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（卡弗里粒子天体物理学与宇宙学研究所，斯坦福大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出利用快速射电暴的行星回波纳米透镜效应（ToA纳秒级周期变化）探测河外系外行星，可测定其质量与轨道参数，并估计光学深度为10^-6，未来SKA二期等有望实现明确探测。
AI中文摘要：
快速射电暴（FRBs）是位于宇宙学距离上的空间和时间上致密的源。作为背景源，它们将对银河系外系外行星的引力透镜效应具有独特的敏感性。我们提出了一种利用行星回波纳米透镜——即当行星绕其宿主恒星运行时，初始FRB与其微透镜回波之间的相对到达时间（ToA）中出现的周期性、纳秒级变化——来探测河外系外行星的方法。对于简单的双透镜模型，我们证明了测量这些ToA波动的振幅和周期能够确定系外行星的质量和轨道参数。FRB对距离银河系十兆秒差距内以及距离FRB宿主十兆秒差距内的透镜体所产生的回波纳米透镜最为敏感，这为在不同红移处探测行星打开了大门。我们估计，至少每百万个FRB中会有一个表现出这种现象（即光学深度$\ au_l = 10^{-6}$）。虽然当前的爆发率和较低的重叠FRB比例使得在短期内进行探测具有挑战性，但即将到来的大规模巡天和下一代阵列（如SKA二期）将使跨宇宙学红移的河外系外行星的明确探测成为可能。
英文摘要：
Fast Radio Bursts (FRBs) are spatially and temporally compact sources at cosmological distances. As background sources, they will be uniquely sensitive to the gravitational lensing of exoplanets outside of our own galaxy. We present a method to detect extragalactic exoplanets using planetary echo nanolensing-periodic, nanosecond-scale variations in the relative time of arrival (ToA) between an initial FRB and its microlensed echo as the planet orbits its host star. For a simple binary lens model, we demonstrate that measuring the amplitude and period of these ToA fluctuations enables a determination of the exoplanet mass and orbital parameters. FRBs will be most sensitive to echo nanolensing by lenses within ten megaparsecs of the Milky Way as well as within ten megaparsecs of the FRB host, opening the door to detections of planets at a range of redshifts. We estimate that at least one in a million FRBs will exhibit this phenomenon (i.e. an optical depth of $τ_l = 10^{-6}$). While current burst rates and low repeating-FRB fractions make a detection challenging in the immediate term, upcoming high-volume surveys and next-generation arrays (such as the SKA Phase 2) will bring the unambiguous detection of extragalactic exoplanets across cosmological redshifts into possibility.
