Self-calibration methods with the CLEAN algorithm have been widely employed in Very Long Baseline Interferometry (VLBI) data processing in order to correct antenna-based amplitude and phase corruptions present in the data. However, human interaction during the conventional CLEAN self-calibration process can impose a strong effective prior, which in turn may produce artifacts within the final image and hinder the reproducibility of final results. In this work, we aim to demonstrate a combined self-calibration and imaging method for VLBI data in a Bayesian inference framework. The method corrects for amplitude and phase gains for each antenna and polarization mode by inferring the temporal correlation of the gain solutions. We use Stokes I data of M87 taken with the Very Long Baseline Array (VLBA) at 43GHz, pre-calibrated using the rPICARD CASA-based pipeline. For antenna-based gain calibration and imaging, we use the Bayesian imaging software resolve. To estimate gain and image uncertainties, we use a Variational Inference method. We obtain a high-resolution M87 Stokes I image at 43GHz in conjunction with antenna-based gain solutions using our Bayesian self-calibration and imaging method. The core with counter-jet structure is better resolved, and extended jet emission is better described compared to the CLEAN reconstruction. Furthermore, uncertainty estimation of the image and antenna-based gains allows us to quantify the reliability of the result. Our Bayesian self-calibration and imaging method is able to reconstruct robust and reproducible Stokes I images and gain solutions with uncertainty estimation by taking into account the uncertainty information in the data.
Bayesian polarization calibration and imaging in very long baseline interferometry
Max-Planck-Institut für Radioastronomie(马克斯·普朗克射电天文研究所);Max Planck Computing and Data Facility(马克斯·普朗克计算与数据中心);Max-Planck-Institut für Astrophysik(马克斯·普朗克天体物理研究所);Technische Universität München (TUM)(慕尼黑工业大学);School of Space Research, Kyung Hee University(庆熙大学宇宙研究学院);Ludwig-Maximilians-Universität(路德维希-马克西米利安大学);Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University(拉布德大学数学、天体物理学和粒子物理研究所天体物理学系);Institut für Experimentalphysik(实验物理研究所)
Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data
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。
Bayesian Imaging for Radio Interferometry with Score-Based Priors
Université de Montréal(蒙特利尔大学);Ciela Institute(谢拉研究所);Mila(米拉研究所);University of Manchester(曼彻斯特大学);Flatiron Institute(熨斗研究所);The Alan Turing Institute(艾伦·图灵研究所);Trottier Space Institute(特罗蒂尔空间研究所);Perimeter Institute(圆周理论物理研究所)
A Python-Based Peeling Framework for Radio Interferometry: Application to uGMRT 650MHz Imaging
Purple Mountain Observatory, Chinese Academy of Sciences(中国科学院紫金山天文台);University of Science and Technology of China(中国科学技术大学);Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Nanjing University(南京大学);National Radio Astronomy Observatory, NRAO(美国国家射电天文台);University of Cape Town(开普敦大学);University of the Western Cape(西开普大学)
The CARMA Paired Antenna Calibration System: Atmospheric Phase Correction for Millimeter Wave Interferometry and its Application to Mapping the Ultraluminous Galaxy Arp 193
IRIS: A Bayesian Approach for Image Reconstruction in Radio Interferometry with expressive Score-Based priors
Université de Montréal(蒙特利尔大学);Mila - Quebec Artificial Intelligence Institute(米拉-魁北克人工智能研究所);Ciela - Montreal Institute for Astrophysical Data Analysis and Machine Learning(CIELA-蒙特利尔天体物理数据分析与机器学习研究所);University of Oxford(牛津大学);Flatiron Institute - Center for Computational Astrophysics(弗拉蒂伦研究所-计算天体物理中心);Perimeter Institute(圆周理论物理研究所);McGill University(麦吉尔大学);University of Manchester(曼彻斯特大学);The Alan Turing Institute(阿兰·图灵研究所)
本文提出贝叶斯成像框架 IRIS,将星系光学图像训练的基于分数模型先验与 uv 空间高斯似然结合,用于 ALMA DSHARP 原行星盘可见度重建,并通过模拟覆盖率测试验证后验校准。
The Bayesian Global Sky Model (B-GSM): Validation of a Data Driven Bayesian Simultaneous Component Separation and Calibration Algorithm for EoR Foreground Modelling
Institute of Astronomy, University of Cambridge(剑桥大学天文学研究所);Cavendish Laboratory, Department of Physics, University of Cambridge(剑桥大学物理系卡文迪许实验室)
A Probabilistic Calibration Procedure for the CORSAIR Polarimeter
Harvard University(哈佛大学);Center for Astrophysics | Harvard & Smithsonian(天体物理中心 | 哈佛与史密森尼学会);Solar Scientific LLC(太阳科学有限责任公司);National Solar Observatory(国家太阳天文台);Institute for Astronomy, University of Hawaii at Manoa(夏威夷大学马诺阿分校天体物理研究所)