SLIDING NOT SLOSHING IN A3744: THE INFLUENCE OF RADIO GALAXIES NGC 7018 AND 7016 ON CLUSTER GAS
SLIDING NOT SLOSHING IN A3744: THE INFLUENCE OF RADIO GALAXIES NGC 7018 AND 7016 ON CLUSTER GAS
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DOI：
10.1088/0004-637x/784/1/36
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发表时间：
2013-12
期刊：
影响因子：
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通讯作者：
D. Worrall;M. Birkinshaw
中科院分区：
文献类型：
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作者：
D. Worrall;M. Birkinshaw
我们提出了新的X射线（钱德拉）和无线电（JVLA）附近的集群A3744的观测。它拥有两个突出的射电星系，其功率在射电模式反馈的关键范围内。来自这些星系的无线电发射终止于到达星系团外缘的浮力卷须，而无线电发射等离子体显然影响了星系团的X射线发射大气。该星团的平均气体温度kT = 3.5 keV，其辐射热光度为3.2 × 1043 erg s−1，这是很高的，但由无线电发射等离子体切割出的100 kpc尺度的空洞显示出不足2%的过剩焓。相反，我们认为与星系群的高速相遇是分散和增加这个非冷核星系团中气体熵的原因。我们没有看到任何证据的冲击，或建立等压气体运动（晃动），但有很多子结构与一个动态活跃的中心区域，包括最明亮的无线电发射。气体加热是明显的方向垂直于推断的线之间的碰撞集团和集群的下降。放射出无线电的卷须沿着不同温度的气体之间的边界，显然润滑了气体流动并抑制了热传递。相遇的第一阶段可能有助于触发射电星系进入目前的活动阶段，在那里我们看到来自核，喷流和热点的X射线。
We present new X-ray (Chandra) and radio (JVLA) observations of the nearby cluster A3744. It hosts two prominent radio galaxies with powers in the range critical for radio-mode feedback. The radio emission from these galaxies terminates in buoyant tendrils reaching the cluster's outer edge, and the radio-emitting plasma clearly influences the cluster's X-ray-emitting atmosphere. The cluster's average gas temperature, of kT = 3.5 keV, is high for its bolometric luminosity of 3.2 × 1043 erg s−1, but the 100 kpc-scale cavity carved out by radio-emitting plasma shows evidence of less than 2% of the excess enthalpy. We suggest instead that a high-velocity encounter with a galaxy group is responsible for dispersing and increasing the entropy of the gas in this non-cool-core cluster. We see no evidence for shocks, or established isobaric gas motions (sloshing), but there is much sub-structure associated with a dynamically active central region that encompasses the brightest radio emission. Gas heating is evident in directions perpendicular to the inferred line of encounter between the infalling group and cluster. The radio-emitting tendrils run along boundaries between gas of different temperature, apparently lubricating the gas flows and inhibiting heat transfer. The first stages of the encounter may have helped trigger the radio galaxies into their current phase of activity, where we see X-rays from the nuclei, jets, and hotspots.