We present LOFAR observations at 120-168 MHz of 42 systems with possible X-ray cavities in their hot atmosphere, of which 17 are groups or ellipticals, 19 are nearby clusters (z 0.3). The X-ray cavities, formed by the radio lobes of the central active galactic nucleus (AGN), are evidence of radio-mode AGN feedback. In the groups and ellipticals sample, half of the systems have X-ray cavities for which no associated lobe emission was detected. Conversely, we report the discovery of large radio lobes in NGC 6338, extending far beyond the emission reported previously in the literature. In the case of the nearby clusters, our observations show that there is little low-frequency radio emission that extends beyond the cavities (e.g. MS 0735.6+7421, A2052). For the first time, we report secure cavity-radio associations in 2A 0335+096, ZwCl 2701, and ZwCl 8276 that strengthens their interpretation as AGN-created cavities. However, in some known cavity systems (e.g. A1795 and ZwCl 3146) we report the lack of detectable low-frequency radio emission associated with the cavities. Our sample of higher redshifts systems is small, and unfortunately the present LOFAR observations are not able to resolve the lobes in many of them. Nevertheless, our sample represents one of the best available for investigating the connection between radio and jet power in radio-mode AGN feedback.

中文翻译：

---

X 射线腔系统的 LOFAR 观测

我们在 120-168 MHz 的频率下对 42 个系统进行了 LOFAR 观测，它们的热大气中可能存在 X 射线腔，其中 17 个是群或椭圆体，19 个是附近的星团 (z 0.3)。由中央活动星系核 (AGN) 的射电瓣形成的 X 射线腔是射电模式 AGN 反馈的证据。在群和椭圆样本中，一半的系统具有 X 射线腔，未检测到相关的波瓣发射。相反，我们报告了 NGC 6338 中大型射电瓣的发现，远远超出了之前文献中报道的发射。在附近星团的情况下，我们的观察表明几乎没有低频无线电辐射超出空腔（例如 MS 0735.6+7421、A2052）。我们首次在 2A 0335+096、ZwCl 2701、和 ZwCl 8276 加强了它们作为 AGN 产生的空腔的解释。然而，在一些已知的空腔系统（例如 A1795 和 ZwCl 3146）中，我们报告了与空腔相关的可检测低频无线电发射的缺乏。我们的更高红移系统的样本很小，不幸的是，目前的 LOFAR 观测无法解析其中许多系统的瓣。尽管如此，我们的样本代表了可用于研究无线电模式 AGN 反馈中无线电和喷气功率之间联系的最佳样本之一。不幸的是，目前的 LOFAR 观测无法解析其中许多的波瓣。尽管如此，我们的样本代表了可用于研究无线电模式 AGN 反馈中无线电和喷气功率之间联系的最佳样本之一。不幸的是，目前的 LOFAR 观测无法解析其中许多的波瓣。尽管如此，我们的样本代表了可用于研究无线电模式 AGN 反馈中无线电和喷气功率之间联系的最佳样本之一。