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 (MACS J0553.4-3342) and SPT CLJ0638-5358 (Abell S0592) are both high-mass lensing clusters that have undergone major mergers. To create science-fidelity images of the galaxy clusters, we performed direction-dependent (DD) calibration and imaging on these ASKAP early science observations using state-of-the-art software killMS and DDFacet. Here, we present our DD calibrated ASKAP radio images of both clusters showing unambiguous giant radio halos with largest linear scales of ${\sim}1$ Mpc. The halo in MACS J0553.4-3342 was previously detected with Giant Metrewave Radio Telescope 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 and sources of seed electrons. This work gives a positive indication of the potential of ASKAP’s Evolutionary Map of the Universe survey in detecting intracluster medium radio sources.

中文翻译：

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ASKAP 揭示了两个合并的 SPT 星系团中的巨大射电晕

澳大利亚平方公里阵列探路者 (ASKAP) 的早期科学观测揭示了与南极望远镜通过 Sunyaev Zel'dovich 信号检测到的两个星团相关的漫射无线电发射的清晰信号：SPT CLJ0553-3342 (MACS J0553.4-3342) ) 和 SPT CLJ0638-5358 (Abell S0592) 都是经过重大合并的高质量透镜集群。为了创建星系团的科学保真度图像，我们使用最先进的软件 killMS 和 DDFacet 对这些 ASKAP 早期科学观测进行了方向相关 (DD) 校准和成像。在这里，我们展示了两个星团的 DD 校准 ASKAP 无线电图像，显示了具有最大线性尺度的明确的巨型无线电晕 ${\sim}1$ 国会议员。MACS J0553.4-3342 中的光晕之前是在 323 MHz 的巨型米波射电望远镜观测中检测到的，但在我们的 ASKAP 图像中显得更加扩展。尽管在该星团的热 X 射线发射中检测到了冲击，但我们发现冲击区域的粒子数密度太低，无法产生无线电冲击。Abell S0592 中的射电光晕是一个新发现，光晕的西南边界与 X 射线检测到的冲击相吻合。我们讨论了这些光晕的起源，同时考虑了强子和湍流再加速模型和光晕的来源种子电子。这项工作积极地表明了 ASKAP 的宇宙进化图调查在检测集群内介质无线电源方面的潜力。