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Ultra-steep spectrum emission in the merging galaxy cluster Abell 1914 ?

机译:合并星系团Abell 1914中的超陡峭光谱发射

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A number of radio observations have revealed the presence of large synchrotron-emitting sources associated with the intra-cluster medium. There is strong observational evidence that the emitting particles have been (re-)accelerated by shocks and turbulence generated during merger events. The particles that are accelerated are thought to have higher initial energies than those in the thermal pool but the origin of such mildly relativistic particles remains uncertain and needs to be further investigated. The galaxy cluster Abell 1914 is a massive galaxy cluster in which X-ray observations show clear evidence of merging activity. We carried out radio observations of this cluster with the LOw Frequency ARay (LOFAR) at 150 MHz and the Giant Metrewave Radio Telescope (GMRT) at 610 MHz. We also analysed Very Large Array (VLA) 1.4 GHz data, archival GMRT 325 MHz data, CFHT weak lensing data and Chandra observations. Our analysis shows that the ultra-steep spectrum source (4C38.39; α ????2), previously thought to be part of a radio halo, is a distinct source with properties that are consistent with revived fossil plasma sources. Finally, we detect some diffuse emission to the west of the source 4C38.39 that could belong to a radio halo.
机译:大量的无线电观测表明,存在与团簇内介质相关的大型同步辐射源。有强有力的观察证据表明,发射粒子已因合并事件期间产生的冲击和湍流而(重新)加速。人们认为,被加速的粒子比热池中的粒子具有更高的初始能量,但是这种轻度相对论粒子的起源仍然不确定,需要进一步研究。星系团Abell 1914是一个巨大的星系团,其中的X射线观察显示出明显的合并活动证据。我们用150 MHz的低频率ARay(LOFAR)和610 MHz的巨型海浪射电望远镜(GMRT)对这个星团进行了无线电观测。我们还分析了1.4 GHz甚大阵列(VLA)数据,325 MHz GMRT存档数据,CFHT弱透镜数据和Chandra观测值。我们的分析表明,以前被认为是无线电晕的一部分的超陡峭光谱源(4C38.39;αβ-2)是一种独特的源,其性质与复活的化石等离子体源一致。最后,我们在源4C38.39的西部检测到一些可能属于无线电晕的散射发射。

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