Diffuse, non-thermal emission in galaxy clusters is increasingly being detected in low-frequency radio surveys and images. We present a new diffuse, steep-spectrum, non-thermal radio source within the cluster Abell 1127 found in survey data from the Murchison Widefield Array (MWA). We perform follow-up observations with the ‘extended’ configuration MWA Phase II with improved resolution to better resolve the source and measure its low-frequency spectral properties. We use archival Very Large Array S-band data to remove the discrete source contribution from the MWA data, and from a power law model fit we find a spectral index of –1.83±0.29 broadly consistent with relic-type sources. The source is revealed by the Giant Metrewave Radio Telescope at 150 MHz to have an elongated morphology, with a projected linear size of 850 kpc as measured in the MWA data. Using Chandra observations, we derive morphological estimators and confirm quantitatively that the cluster is in a disturbed dynamical state, consistent with the majority of phoenices and relics being hosted by merging clusters. We discuss the implications of relying on morphology and low-resolution imaging alone for the classification of such sources and highlight the usefulness of the MHz to GHz radio spectrum in classifying these types of emission. Finally, we discuss the benefits and limitations of using the MWA Phase II in conjunction with other instruments for detailed studies of diffuse, steep-spectrum, non-thermal radio emission within galaxy clusters.

中文翻译：

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Murchison 宽场阵列检测 Abell 1127 内的陡谱、漫射、非热无线电发射

在低频无线电勘测和图像中越来越多地检测到星系团中的漫射非热辐射。我们在来自默奇森宽场阵列 (MWA) 的调查数据中发现了 Abell 1127 星团内的一种新的漫射、陡光谱、非热射电源。我们使用具有更高分辨率的“扩展”配置 MWA Phase II 进行后续观察，以更好地解析源并测量其低频光谱特性。我们使用存档的超大阵列 S 波段数据从 MWA 数据中去除离散源贡献，从幂律模型拟合中，我们发现 –1.83±0.29 的光谱指数与遗迹型源大体一致。巨型米波射电望远镜在 150 MHz 处显示该源具有细长的形态，在 MWA 数据中测得的预计线性尺寸为 850 kpc。使用钱德拉观察，我们推导出形态估计量并定量地确认集群处于受扰动的动态状态，这与合并集群所承载的大多数凤凰和遗物一致。我们讨论了仅依靠形态学和低分辨率成像对此类源进行分类的意义，并强调了 MHz 至 GHz 无线电频谱在对这些类型的发射进行分类时的有用性。最后，我们讨论了将 MWA Phase II 与其他仪器结合使用以详细研究星系团内的漫射、陡光谱、非热无线电发射的好处和局限性。