论文标题
PDS70光盘中的可变结构和射击图像恢复中的不确定性
Variable structure in the PDS70 disc and uncertainties in radio-interferometric image restoration
论文作者
论文摘要
深层ALMA观察结果显示，PDS70盘中心腔中的紧凑型MM波长信号与未解决的HALPHA发射对齐，被认为源于PDS70C周围的周围行销盘（CPD）。我们通过替代成像策略重新访问PDS70C上的可用ALMA数据，并特别注意不确定性以及所谓的“ JVM校正”的影响，这被认为可以改善恢复的图像的动态范围。我们还提出了一个多个观看性数据的对齐和关节成像的程序。我们发现JVM校正夸大了数据的峰值信噪比，高达10倍。在PDS70的情况下，我们从2019年7月的数据中恢复了PDS70C的检测，但仅在8sigma。但是，它在2017年12月的未进行检测表明，在1.75yr时跨度上，PDS70C的变化至少为42％+-13％，因此与Halpha变异性的模型相似。我们还在内部圆盘上拾取了细小的结构，因此其峰偏离了圆盘中心〜0.04“。内盘也是可变的，我们暂时将其归因于开普勒旋转以及固有的形态变化。
The compact mm-wavelength signal in the central cavity of the PDS70 disc, revealed by deep ALMA observations, is aligned with unresolved Halpha emission, and is thought to stem from a circum-planetary disc (CPD) around PDS70c. We revisit the available ALMA data on PDS70c with alternative imaging strategies, and with special attention to uncertainties and to the impact of the so-called "JvM correction", which is thought to improve the dynamic range of restored images. We also propose a procedure for the alignment and joint imaging of multi-epoch visibility data. We find that the JvM correction exaggerates the peak signal-to-noise of the data, by up to a factor of 10. In the case of PDS70, we recover the detection of PDS70c from the July 2019 data, but only at 8sigma. However, its non-detection in Dec. 2017 suggests that PDS70c is variable by at least 42%+-13% over a 1.75yr time-span, so similar to models of the Halpha variability. We also pick up fine structure in the inner disc, such that its peak is offset by ~ 0.04" from the disc centre. The inner disc is variable too, which we tentatively ascribe to Keplerian rotation as well as intrinsic morphological changes.
