Interaction between the intergalactic medium and central radio source in the NGC 4261 group of galaxies IGM-radio source interaction in NGC 4261
Interaction between the intergalactic medium and central radio source in the NGC 4261 group of galaxies IGM-radio source interaction in NGC 4261
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NGC 4261 星系群中星系间介质和中央射电源之间的相互作用 NGC 4261 中的 IGM-射电源相互作用
DOI：
10.1111/j.1365-2966.2011.19239.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
O'Sullivan E
中科院分区：
文献类型：
--
作者：
O'Sullivan E
利用钱德拉和xmm -牛顿x射线天文台的观测结果，我们研究了NGC 4261星系群内部介质和中心射电源之间的相互作用。我们证实了与射电瓣相关的空腔的存在，并估计它们的焓为~ 2.4× 1058 erg。喷流的机械输出功率≥1043 erg s−1，至少比叶状星云所在区域的冷却光度高60倍。我们确定了包围叶状体的压缩气体的边缘，但发现它们与周围环境之间没有统计学上显著的温差，这表明叶状体的膨胀速度近似于音速（）。根据同步加速器最小能量密度理论，无线电波瓣的视压力比群内介质的视压力低5倍。如果热气体的携带在叶状等离子体中提供额外的非辐射粒子，则可以实现压力平衡，但加热这些粒子所需的能量将是射电源输出机械能的20%。NGC 4261有一个相对致密的冷核，它应该被归类为星系日冕。日冕能够为活动核提供燃料的时间比推断的源寿命长得多，但只能通过活动星系核（AGN）或传导进行低效率加热。射电叶的膨胀影响了星系中气体的结构，压缩和移动了日冕的物质，而没有引起明显的激波加热，并从喷流的近邻排出气体。我们讨论了这种环境对AGN爆发持续时间的可能影响，并考虑了可能导致核活动停止的机制。
Using observations from the Chandra and XMM–Newton X-ray observatories, we examine the interaction between the intragroup medium and central radio source in the nearby NGC 4261 galaxy group. We confirm the presence of cavities associated with the radio lobes and estimate their enthalpy to be∼ 2.4× 1058 erg. The mechanical power output of the jets is≥ 1043 erg s− 1, at least a factor of 60 greater than the cooling luminosity in the region the lobes inhabit. We identify rims of compressed gas enclosing the lobes, but find no statistically significant temperature difference between them and their surroundings, suggesting that the lobe expansion velocity is approximately sonic (). The apparent pressure of the radio lobes, based on the synchrotron minimum energy density argument, is a factor of 5 lower than that of the intragroup medium. Pressure balance could be achieved if the entrainment of thermal gas provided additional non-radiating particles in the lobe plasma, but the energy required to heat these particles would be∼ 20 per cent of the mechanical energy output of the radio source. NGC 4261 has a relatively compact cool core, which should probably be categorized as a galactic corona. The corona is capable of fuelling the active nucleus for considerably longer than the inferred source lifetime, but can be only inefficiently heated by the active galactic nucleus (AGN) or conduction. The expansion of the radio lobes has affected the structure of the gas in the galaxy, compressing and moving the material of the corona without causing significant shock heating, and expelling gas from the immediate neighbourhood of the jets. We discuss the possible implications of this environment for the duration of the AGN outburst and consider mechanisms which might lead to the cessation of nuclear activity.