在144兆赫洛克曼霍尔场的深亚弧秒宽场成象
Deep sub-arcsecond widefield imaging of the Lockman Hole field at 144 MHz
摘要：
高质量的低频无线电观测有望推进我们对天体物理学许多重要课题的理解，包括活动星系核的生命周期、喷流中的粒子加速过程、恒星形成的历史和系外行星磁层。目前领先的低频勘测达到几角秒的角分辨率。然而，这种分辨率还不足以详细研究更紧凑和更遥远的源。因此，亚弧秒分辨率是推进这些领域的下一个里程碑。低射频的最大挑战是电离层。如果没有适当的校正，电离层视宁度会使图像模糊到角秒甚至角分的尺度。此外，以该分辨率绘制低频射电望远镜度尺度视场所需的图像尺寸远远大于典型的软件和硬件目前能够处理的尺寸。在这里，我们提出了第一次（尽我们所知）在低射频宽视场亚弧秒成像。我们在几十个单独的方向得到电离层校正，并在成像过程中有效地使用最近开发的成像算法（arXiv：1407.1943，arXiv：1909.07226）。我们证明了我们的方法，将其应用于国际低频阵列（LOFAR）望远镜（ILT）（arXiv：1305.3550）的8小时观测。这样做，我们已经取得了一个敏感的$7.4\ \mathrm{deg}^2$ $144\ \mathrm{MHz}$地图的分辨率$0.3''$达到$25\ μ\mathrm{Jy\ beam}^{-1}$附近的相位中心。用于生成此图像的估计$250,000$核心小时完全符合可用计算设施的预算。这一结果将使整个北部低频天空的未来映射在亚弧秒分辨率。
英文摘要：
High quality low-frequency radio surveys have the promise of advancing our understanding of many important topics in astrophysics, including the life cycle of active galactic nuclei (AGN), particle acceleration processes in jets, the history of star formation, and exoplanet magnetospheres. Currently leading low-frequency surveys reach an angular resolution of a few arcseconds. However, this resolution is not yet sufficient to study the more compact and distant sources in detail. Sub-arcsecond resolution is therefore the next milestone in advancing these fields. The biggest challenge at low radio frequencies is the ionosphere. If not adequately corrected for, ionospheric seeing blurs the images to arcsecond or even arcminute scales. Additionally, the required image size to map the degree-scale field of view of low-frequency radio telescopes at this resolution is far greater than what typical soft- and hardware is currently capable of handling. Here we present for the first time (to the best of our knowledge) widefield sub-arcsecond imaging at low radio frequencies. We derive ionospheric corrections in a few dozen individual directions and apply those during imaging efficiently using a recently developed imaging algorithm (arXiv:1407.1943, arXiv:1909.07226). We demonstrate our method by applying it to an eight hour observation of the International LOw Frequency ARray (LOFAR) Telescope (ILT) (arXiv:1305.3550). Doing so we have made a sensitive $7.4\ \mathrm{deg}^2$ $144\ \mathrm{MHz}$ map at a resolution of $0.3''$ reaching $25\ μ\mathrm{Jy\ beam}^{-1}$ near the phase centre. The estimated $250,000$ core hours used to produce this image, fit comfortably in the budget of available computing facilities. This result will enable future mapping of the entire northern low-frequency sky at sub-arcsecond resolution.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
