大质量星系团弥散辐射研究

Detection of Diffuse Emission in Massive Galaxy Clusters with Radio Interferometers

星系团中的弥散辐射通常以位于中心区域的射电晕或周围区域的射电遗迹形式存在。根据星系团弥散辐射的陡谱特性,通过宽带低频射电波段的观测,能够得到其中射电晕及射电遗迹的频谱特征,从而帮助理解星系团的形成与演化过程。通过分析默奇森宽场阵列(Murchison Widefield Array,MWA)、澳大利亚望远镜阵列(Australia Telescope Compact Array,ATCA)在射电波段对位于红移z=0.098的星系团SPT J2201-5956和位于z=0.232的星系团SPT J2023-5535的观测数据,得到了对应两个星系团的弥散辐射特性。分析结果表明SPT J2201-5956中弥散辐射的谱指数为-1.68-0.27+0.27,其来源可能为星系团中的死亡星系;SPT J2023-5535中弥散辐射的谱指数为-1.21-0.02+0.02,且其辐射位于星系团的中心区域,因此可以认为该星系团中的弥散源是射电晕候选体。

Galaxy clusters have long been known to host diffuse,steep spectrum,synchrotron radio emission either in the central part of the cluster in the case of radio halos,or on the periphery in the case of radio relics.Detection of diffuse cluster emission across a wide range of frequency can help with understanding the formation of radio halos and radio relics,and even the formation of galaxy clusters and the Universe.We present the detection of diffuse radio emission associated with the massive galaxy clusters SPT J2201-5956 and SPT J2023-5535 by using wide-band data from MWA at 70~300 MHz and ATCA at 2.1 GHz.We detected a radio emission of 0.87 Mpc2 within the cluster SPT J2201-5956,and 0.9 Mpc2 in extent associated with SPT J2023-5535.We characterized the spectral index of the diffuse emission,and found SPT J2201-5956 with α=-1.68-0.27+0.27,SPT J2023-5535 with α=-1.21-0.02+0.02.The origins of the diffuse emission in SPT J2201-5956 could be dead galaxies,while the diffuse emission in SPT J2023-5535 could be a radio halo candidate.