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arXiv 2407.14873astro-ph.IM
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甚长基线干涉测量中的贝叶斯自校准与成像

Bayesian self-calibration and imaging in Very Long Baseline Interferometry

Jong-Seo Kim, Aleksei S. Nikonov, Jakob Roth, Torsten A. Ensslin, Michael Janssen, Philipp Arras, Hendrik Mueller, Andrei P. Lobanov

AI总结:

本文提出在贝叶斯推断框架下结合变分推断,对VLBI数据进行天线增益自校准与成像,并在M87的VLBA 43GHz数据上获得比CLEAN更稳健、可复现且带不确定性估计的Stokes I图像。

摘要:

在甚长基线干涉测量(VLBI)数据处理中,基于CLEAN算法的自校准方法已被广泛用于校正数据中存在的天线基振幅和相位误差。然而,传统CLEAN自校准过程中的人为干预会施加很强的有效先验,从而可能在最终图像中产生伪影,并妨碍最终结果的可复现性。在本工作中,我们旨在展示一种在贝叶斯推断框架下对VLBI数据进行自校准与成像相结合的方法。该方法通过推断增益解的时间相关性,对每个天线和偏振模式的振幅与相位增益进行校正。我们使用甚长基线阵列(VLBA)在43GHz上观测到的M87 Stokes I数据,这些数据已通过基于CASA的rPICARD流水线进行了预校准。对于基于天线的增益校准和成像,我们使用贝叶斯成像软件resolve。为了估计增益和图像的不确定性,我们采用变分推断方法。利用我们的贝叶斯自校准与成像方法,我们获得了43GHz的M87 Stokes I高分辨率图像以及基于天线的增益解。与CLEAN重建相比,带有反向喷流结构的核心被更好地分辨,延展喷流辐射也被更好地描述。此外,图像和基于天线的增益的不确定性估计使我们能够量化结果的可靠性。我们的贝叶斯自校准与成像方法通过考虑数据中的不确定性信息,能够重建稳健且可复现的Stokes I图像和增益解,并提供不确定性估计。

英文摘要:

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.

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