Radio bubbles in clusters of galaxies
Radio bubbles in clusters of galaxies
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DOI：
10.1111/j.1365-2966.2005.09673.x
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发表时间：
2005-10
影响因子：
4.8
通讯作者：
R. Dunn;A. Fabian;G. I. F. Astronomy;Cambridge;Nrao;Socorro;K. Institute;California
中科院分区：
文献类型：
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作者：
R. Dunn;A. Fabian;G. I. F. Astronomy;Cambridge;Nrao;Socorro;K. Institute;California
我们扩展了我们早期在具有明显无线电气泡的星团核心上的工作，在我们的样本中添加了更多的活跃气泡，即具有GHz无线电发射的气泡，并且还研究了“幽灵气泡”，即没有GHz无线电发射的气泡。我们已经确定了k，它是总粒子能量与在10mhz和10ghz之间辐射的电子能量之比。对活性气泡年龄的限制确定了能量因子k与体积填充因子的比值在1范围内。k / f。1000. 在假设射电等离子体和周围的热x射线气体之间存在压力平衡的情况下，没有一个射电叶具有相对论性粒子和磁场之间的均分。对数据进行蒙特卡罗模拟得出的结论是，目前的样本中没有足够的气泡，无法确定总体的形状。对我们样本中的幽灵气泡的分析表明，总的来说，它们比活跃气泡具有更高的k/f上限，特别是与同一簇中的气泡相比。一项对最亮的55个星团样本的研究表明，17个，可能是20个星团需要某种形式的加热，因为它们的中心冷却时间很短，只有63 Gyr，中心温度下降很大，Tcentre/Touter < 1/2。其中12个（70%）至15个（75%）存在泡沫。这表明在这种簇中气泡的寿命周期很大，它们可以在加热过程中起主要作用。
We extend our earlier work on cluster cores with distinct radio bubbles, adding more active bubbles, i.e. those with GHz radio emission, to our sample, and also investigating “ghost bubbles,” i.e. those without GHz radio emission. We have determined k, which is the ratio of the total particle energy to that of the electrons radiati ng between 10 MHz and 10 GHz. Constraints on the ages of the active bubbles confirm that the ratio of the energy factor, k, to the volume filling factor, f lies within the range 1 . k/f . 1000. In the assumption that there is pressure equilibrium between the radio-emitting plasma and the surrounding thermal X-ray gas, none of the radio lobes has equipartition between the relativistic particles and the magnetic field. A Monte-Carlo simulation of the data led t o the conclusion that there are not enough bubbles present in the current sample to be able to determine the shape of the population. An analysis of the ghost bubbles in our sample showed that on the whole they have higher upper limits on k/f than the active bubbles, especially when compared to those in the same cluster. A study of the Brightest 55 cluster sample shows that 17, possibly 20, clusters required some form of heating as they have a short central cooling time, tcool 6 3 Gyr, and a large central temperature drop, Tcentre/Touter < 1/2. Of these between 12 (70 per cent) and 15 (75 per cent), contain bubbles. This indicates that the du ty cycle of bubbles is large in such clusters and that they can play a major role in the heating process.