论文标题
ASKAP揭示了两个合并的SPT星系簇中的巨型无线电光环 - 为方向依赖的管道提供了理由 -
ASKAP reveals giant radio halos in two merging SPT galaxy clusters -- Making the case for a direction-dependent pipeline --
论文作者
论文摘要
澳大利亚平方公里阵列探路者（ASKAP）的早期科学观察结果揭示了通过其Sunyaev Zel'Dovich信号通过其Southole望远镜检测到的两个群集相关的弥漫性无线电发射信号。 SPT CLJ0553-3342（MACSJ0553.4-3342）和SPT CLJ0638-5358（Abell S0592）都是经历了主要合并的高质量镜头群。为了改善这些ASKAP早期科学观察的数据产品，并创建了Galaxy簇的科学前景图像，我们使用最先进的软件{\ sc Killms}和{\ sc ddfacet}执行了方向依赖（DD）校准和成像。我们发现，在定向校准后，ASKAP图像中的伪影大大降低了。在这里，我们介绍了两个簇的DD校准的ASKAP无线电图像，显示了$ \ sim1 $ 〜mpc的最大线性尺度的明确的巨型无线电光环。先前在323 MHz的GMRT观测值中检测到MacSJ0553.4-3342中的光环，但在我们的ASKAP图像中似乎更扩展。尽管该集群的热X射线发射中检测到了冲击，但我们发现冲击区域中的粒子数密度太低，无法产生无线电冲击。 Abell S0592的电台光环是一个新的发现，光环的西南边界恰逢X射线检查中的震惊。我们讨论了这些光晕的起源，考虑了hadronic和湍流重新加速模型以及\ textit {seed}电子的来源。这项工作表明了Askap宇宙宇宙进化图（EMU）在检测群内培养基无线电源中的潜力，并在利用第三代校准技术后展示了数据产品的改善。
Early science observations from the Australian Square Kilometre Array Pathfinder (ASKAP) have revealed clear signals of diffuse radio emission associated with two clusters detected by the South Pole Telescope via their Sunyaev Zel'dovich signal. SPT CLJ0553-3342 (MACSJ0553.4-3342) and SPT CLJ0638-5358 (Abell S0592) are both high-mass lensing clusters that have undergone major mergers. To improve the data products of these ASKAP early science observations and create science-fidelity images of the galaxy clusters, we performed direction-dependent (DD) calibration and imaging using state-of-the-art software {\sc killMS} and {\sc DDFacet}. We find that artefacts in the ASKAP images are greatly reduced after directional calibration. Here we present our DD calibrated ASKAP radio images of both clusters showing unambiguous giant radio halos with largest linear scales of $\sim1$~Mpc. The halo in MACSJ0553.4-3342 was previously detected with GMRT observations at 323 MHz, but appears more extended in our ASKAP image. Although there is a shock detected in the thermal X-ray emission of this cluster, we find that the particle number density in the shocked region is too low to allow for the generation of a radio shock. The radio halo in Abell S0592 is a new discovery, and the Southwest border of the halo coincides with a shock detected in X-rays. We discuss the origins of these halos considering both the hadronic and turbulent re-acceleration models as well as sources of \textit{seed} electrons. This work gives a positive indication of the potential of ASKAP's Evolutionary Map of the Universe (EMU) survey in detecting intracluster medium radio sources, and showcases the improvement in data products after utilising third-generation calibration techniques.
