标题： 两个相交的射电壳：星系合并激波的遗迹？ 显示英文标题

标题： Two intersecting radio shells: relics of galaxy merger shocks ?

摘要： 我们发现了两个相交的射电壳层，可能是射电遗迹，围绕着一个由一个大椭圆星系主导的紧凑星系群。这些壳层表现为部分边缘明亮的环，直径约为240"（720 kpc），看起来像一对奇怪的射电圆环。中心星系WISEA J184105.19-654753.8显示出相互作用的迹象，是射电明亮的，恒星质量为3.1 x 10^11 Msun（红移zphot = 0.18），位于相交区域。双射电壳层系统，我们称之为ORC J1841-6547（也称为ORC 6），是在使用澳大利亚平方公里阵列探路者（ASKAP）上的相位阵列馈源获得的944 MHz射电连续谱图像中检测到的。更显著的西北壳层可能与X射线探测有关，而较弱的东南壳层在非射电波长上没有对应物。我们提出，来自星系合并的向外运动冲击波进入星系间介质，重新激活了遗迹射电瓣，这可能是观测到的射电壳层的一种可能形成情景。我们得出结论，至少一些ORC是位于星系群外围的冲击波驱动的遗迹，它们起源于最亮星系群星系的合并演化过程中。 显示英文摘要

摘要： We present the discovery of two intersecting radio shells, likely radio relics, surrounding a compact galaxy group dominated by a massive elliptical galaxy. The shells present as partial, edge-brightened rings with diameters of about 240" (720 kpc) each and resemble a pair of odd radio circles. The central galaxy, WISEA J184105.19-654753.8, which shows signs of interactions, is radio bright, has a stellar mass of 3.1 x 10^11 Msun (for a redshift of zphot = 0.18) and is located in the intersect region. The double radio shell system, which we refer to as ORC J1841-6547 (also known as ORC 6), was detected in 944 MHz radio continuum images obtained with Phased Array Feeds on the Australian Square Kilometre Array Pathfinder (ASKAP). The more prominent, north-western shell may be associated with an X-ray detection, while the weaker, south-eastern shell has no counterpart at non-radio wavelength. We propose outwards moving shocks from galaxy mergers driving into the intragroup medium, re-energising relic radio lobes, as a possible formation scenario for the observed radio shells. We conclude that at least some ORCs are shock-energised relics in the outskirts of galaxy groups, which originate during the merger evolution of the brightest group galaxy.