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arXiv 1701.04096astro-ph.COastro-ph.GAastro-ph.HE
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HST前沿场星系团MACS J0717 .5+3745的Chandra和JVLA观测

Chandra and JVLA observations of HST Frontier Fields cluster MACS J0717.5+3745

R. J. van Weeren, G. A. Ogrean, C. Jones, W. R. Forman, F. Andrade-Santos, Connor J. J. Pearce, A. Bonafede, M. Brüggen, E. Bulbul, T. E. Clarke, E. Churazov, L… 展开作者

R. J. van Weeren, G. A. Ogrean, C. Jones, W. R. Forman, F. Andrade-Santos, Connor J. J. Pearce, A. Bonafede, M. Brüggen, E. Bulbul, T. E. Clarke, E. Churazov, L. David, W. A. Dawson, M. Donahue, A. Goulding, R. P. Kraft, B. Mason, J. Merten, T. Mroczkowski, P. E. J. Nulsen, P. Rosati, E. Roediger, S. W. Randall, J. Sayers, K. Umetsu, A. Vikhlinin, A. Zitrin

摘要:

为了研究并合星系团中热成分和非热成分之间的关系,我们对HST前沿场星系团MACS J0717.5+3745进行了深JVLA和Chandra观测。钱德拉的图像显示了一个复杂的合并事件,至少有四个组成部分属于不同的合并子集群。在星系团的西北方,距离中心$\sim 0.7$ Mpc,有一个冲压压力剥离的核心,它似乎是从一个星系丝的方向进入ICM到东南方向之后穿过了星系团的致密部分。我们检测到一个密度不连续NNE的核心,我们推测这是与冷锋。我们的射电图像揭示了这个星团中复杂的射电遗迹和射电晕的新细节。此外,我们还发现了几个新的100-300千秒差距的射电源。其中一些星系似乎与主射电遗迹相连,而另一些星系则嵌入射电晕内或投射到射电晕上。一个窄角尾射电星系(NAT)是星系团的成员,位于射电遗迹的中心。这个活动星系核陡峭的频谱拖尾导致了大射电遗迹,在那里射电频谱再次重叠。NAT射电星系和遗迹之间的这种形态学联系为化石电子的再加速(复兴)提供了证据。钱德拉在遗迹附近探测到的热$\gtrsim 20$ keV ICM气体的存在为这种再加速场景提供了额外的支持。

英文摘要:

To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. NW of the cluster, $\sim 0.7$ Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the ICM from the direction of a galaxy filament to the SE. We detect a density discontinuity NNE of this core which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100-300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this AGN leads into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot $\gtrsim 20$ keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.

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