发表机构
Universidad Nacional Autónoma de México, Instituto de Radioastronomía y Astrofísica; National Radio Astronomy Observatory（墨西哥国立自治大学，射电天文与天体物理研究所; 美国国家射电天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用VLA 10GHz GOODS-N图像，发现高分辨率射电巡天中虚假源过剩源于不完整uv采样导致的脏波束旁瓣相关噪声，而非成像方法本身，未来巡天需兼顾高分辨率与密集uv覆盖。
AI 中文摘要
盲河外星系射电连续谱巡天日益以亚角秒级角分辨率进行。然而，这些巡天中包含的虚假源数量远超纯高斯噪声统计的预期。我们利用卡尔·G·扬斯基甚大阵列（VLA）获得的10GHz GOODS-N马赛克图像研究了这些虚假探测的起源，该图像达到0.22角秒的固有角分辨率，并表现出近似高斯的像素噪声分布。我们表明，高角分辨率下虚假源比例增加的部分原因自然来自于独立分辨单元数量的增多，而主波束响应相关的残余宽场成像效应仅贡献较小。然而，即使考虑了这些效应，观测到的虚假探测比例仍比高斯噪声预测高出数倍。对噪声自相关函数的分析揭示，uv覆盖相对稀疏的图像保留了显著的脏波束旁瓣，这些旁瓣引入相关噪声波动，大幅增加了虚假探测的概率。我们得出结论，虚假源的过剩是不完整uv采样的内在结果，而非成像方法本身所致，这凸显了未来深场射电连续谱巡天不仅需要高角分辨率，还需要足够密集的uv覆盖以最小化虚假探测。
英文摘要
Blind extragalactic radio continuum surveys are increasingly conducted at sub-arcsecond angular resolutions. However, these surveys contain substantially more spurious sources than expected from purely Gaussian noise statistics. We investigate the origin of these false detections using the 10GHz GOODS-N mosaic obtained with the Karl G. Jansky Very Large Array (VLA), which reaches a native angular resolution of 0.22arcsec and exhibits a nearly Gaussian pixel-noise distribution. We show that part of the increase in the spurious-source fraction at high angular resolution arises naturally from the larger number of independent resolution elements, while residual wide-field imaging effects associated with the primary-beam response make only a modest contribution. Nevertheless, even after accounting for these effects, the observed fraction of false detections remains several times higher than predicted for Gaussian noise. An analysis of the noise autocorrelation function reveals that images with relatively sparse uv coverage retain significant dirty-beam sidelobes that introduce correlated noise fluctuations, substantially increasing the probability of false detections. We conclude that the excess of spurious sources is an intrinsic consequence of incomplete uv sampling rather than the imaging methodology itself, highlighting that future deep radio continuum surveys require not only high angular resolution but also sufficiently dense uv coverage to minimize spurious detections.
CommentsAccepted for publication in the Revista Mexicana de Astronomía y Astrofísica (RMxAA)
