无线电干涉测量中的校准伪像。I. WSRT数据中的虚源
Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data
摘要：
这项工作研究了一类特殊的人工制品，或鬼源，在无线电干涉图像。韦斯特博克综合射电望远镜（Westerbork Synthesis Radio Telescope，WSRT）的早期观测（和模拟）表明，这些都是由于不完整的天空模型校准造成的。一个理论框架的推导，验证了这一建议，并提供了在两个源的情况下，鬼形成的预测。预测被发现准确地匹配模拟的结果，并定性地再现了以前在观测数据中看到的鬼。该理论还提供了许多以前令人困惑的功能，这些文物（规则的几何形状，PSF样旁瓣，似乎独立于模型通量）的解释，并表明，所观察到的现象影响未建模的源通量抑制是由于相同的机制。我们证明，这种鬼形成机制是校准的一个基本特征，并表现出特别强大的和本地化的签名，由于阵列冗余。在某种程度上，这种机制将影响所有的观测（包括那些非冗余阵列），但在大多数情况下，鬼仍然隐藏在噪音或其他仪器伪影掩盖。这种错误对未来的深层观测的影响进行了讨论。
英文摘要：
This work investigates a particular class of artefacts, or ghost sources, in radio interferometric images. Earlier observations with (and simulations of) the Westerbork Synthesis Radio Telescope (WSRT) suggested that these were due to calibration with incomplete sky models. A theoretical framework is derived that validates this suggestion, and provides predictions of ghost formation in a two-source scenario. The predictions are found to accurately match the result of simulations, and qualitatively reproduce the ghosts previously seen in observational data. The theory also provides explanations for many previously puzzling features of these artefacts (regular geometry, PSF-like sidelobes, seeming independence on model flux), and shows that the observed phenomenon of flux suppression affecting unmodelled sources is due to the same mechanism. We demonstrate that this ghost formation mechanism is a fundamental feature of calibration, and exhibits a particularly strong and localized signature due to array redundancy. To some extent this mechanism will affect all observations (including those with non-redundant arrays), though in most cases the ghosts remain hidden below the noise or masked by other instrumental artefacts. The implications of such errors on future deep observations are discussed.
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。
