We analysed the deep archival Chandra observations of the high-temperature galaxy cluster Abell 2319 to investigate the prominent cold front in its core. The main sharp arc of the front shows wiggles, or variations of the radius of the density jump along the arc. At the southern end of the arc is a feature that resembles a Kelvin–Helmholtz (KH) eddy, beyond which the sharp front dissolves. These features suggest that KH instabilities develop at the front. Under this assumption, we can place an upper limit on the ICM viscosity that is several times below the isotropic Spitzer value. Other features include a split of the cold front at its northern edge, which may be another KH eddy. There is a small pocket of hot, less-dense gas inside the cold front, which may indicate a ‘hole’ in the front’s magnetic insulation layer that lets the heat from the outer gas to penetrate inside the front. Finally, a large concave brightness feature south-west of the cluster core can be caused by the gas-dynamic instabilities. We speculate that it can also be an inner boundary of a giant AGN bubble, similar to that in Ophiuchus. If the latter interpretation is supported by better radio data, this could be a remnant of another extremely powerful AGN outburst.

中文翻译：

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Abell 2319 核心的子结构

我们分析了高温星系团 Abell 2319 的深层档案钱德拉观测资料，以研究其核心中突出的冷锋。正面的主要锐弧显示出摆动，或沿弧的密度跳跃半径的变化。在弧的南端是一个类似于开尔文-亥姆霍兹 (KH) 涡流的特征，在该涡流之外，锋利的锋面消失了。这些特征表明 KH 不稳定性在前沿发展。在这种假设下，我们可以将 ICM 粘度的上限设置为低于各向同性 Spitzer 值的数倍。其他特征包括冷锋在其北部边缘的分裂，这可能是另一个 KH 涡流。冷锋内部有一小团热的、密度较低的气体，这可能表明前部的磁绝缘层上有一个“洞”，可以让来自外部气体的热量渗透到前部内部。最后，星团核心西南方向的一个大的凹面亮度特征可能是由气体动力学不稳定性引起的。我们推测它也可能是一个巨大的活动星系核气泡的内部边界，类似于蛇夫座中的那个。如果后一种解释得到更好的无线电数据的支持，这可能是另一个极其强大的 AGN 爆发的残余。