AI 中文总结
利用EMU和DINGO巡天数据，研究GAMA星系群弥散射电辐射，采用多分辨率滤波技术，识别出46个候选星系群，发现射电功率与晕质量有微弱正趋势，揭示不同物理过程主导，为低质量环境非热过程提供新约束。
AI 中文摘要
弥散射电辐射是研究大尺度结构中非热过程的有力工具，但其在星系群中的性质仍知之甚少。本文利用宇宙演化地图（EMU）的943MHz深度射电连续谱数据和中性气体起源深度调查（DINGO）的1.37GHz数据，研究了从GAMA巡天中选取的400个红移z<0.1的星系群中的弥散射电辐射。采用多分辨率滤波技术抑制致密射电源，增强与星系群介质相关的扩展低表面亮度辐射。在群半径内测量积分通量密度，并用随机控制区域量化背景波动。多数系统未被探测到，但识别出46个有候选弥散辐射的星系群，其射电功率跨度为10^19 - 10^24 W Hz^-1。叠加测量揭示了射电功率与晕质量之间的微弱正趋势。观测到的辐射水平高于星系团标度关系的简单外推，表明不同物理过程在星系群中占主导。此外，星系群中最大质量星系的恒星质量比和早型星系比例表明这些星系群相对年轻且在演化，星系相互作用和合并可能为辐射提供能量。与磁流体动力学模拟的比较表明，仅靠激波加速无法解释观测到的辐射，化石等离子体重加速和群尺度动力学活动起着重要作用。这些结果表明弥散射电辐射在不可忽略比例的星系群中存在，为低质量环境中的非热过程提供了新约束。
英文摘要
Diffuse radio emission provides a powerful probe of non-thermal processes in the large-scale structure, yet its properties in galaxy groups remain poorly constrained. Using deep 943 MHz radio continuum data from the Evolutionary Map of the Universe (EMU) and 1.37 GHz data from the Deep Investigations of Neutral Gas Origins (DINGO) survey, we investigate diffuse radio emission in 400 galaxy groups selected from the GAMA survey at $z < 0.1$. We employ a multi-resolution filtering technique to suppress compact radio sources and enhance extended, low-surface-brightness emission associated with the intra group medium. Integrated flux densities are measured within group radii, and background fluctuations are quantified using random control regions. While most systems yield non-detections, we identify 46/400 galaxy groups with candidate diffuse emission, spanning radio powers of $10^{19}-10^{24}\,\mathrm{W\,Hz^{-1}}$. Stacked measurements reveal a weak positive trend between radio power and halo mass. The observed emission levels lie above simple extrapolations of cluster scaling relations, suggesting that different physical processes dominate in the group regime. Additionally, stellar mass ratios of the most massive galaxies in the group and Early Type Galaxy fractions suggest that these galaxy groups are relatively young, evolving systems where galaxy interactions and mergers may power the emission. Comparisons with Magneto Hydrodynamical simulations indicate shock acceleration alone cannot explain the observed emission, pointing to an important role for fossil plasma re-acceleration and group-scale dynamical activity. These results demonstrate diffuse radio emission is present in a non-negligible fraction of galaxy groups, providing new constraints on non-thermal processes in low-mass environments.
CommentsAccepted for publication in MNRAS
