The onset of a powerful radio source in a central cluster galaxy
The onset of a powerful radio source in a central cluster galaxy
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中央星团星系中出现强大的射电源
DOI：
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发表时间：
1997
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影响因子：
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通讯作者：
C. Crawford
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作者：
M. Bremer;A. Fabian;C. Crawford
我们讨论中央星团星系中强大的法纳洛夫 - 莱利 (FR) II 型射电源的出现对周围星团气体的影响。我们表明，如果源位于具有强冷却流的星团中心，则可以解释强大的高红移射电源的许多观察到的特性。冷却流提供了现成的冷气体源，可以成为类星体和星系中光学发射线和吸收线云的来源，以及在某些来源中隐藏中央引擎的方法。这。情景预测了无线电源尺寸与相关光学吸收的存在（或缺乏）以及任何对准的光学光的强度之间的相关性。特别是，强烈的 Lyoc 吸收在射电星系中应该很常见；无线电发射区域越小，吸收越强。如果类星体中看到的大部分相关吸收来自周围的冷却流，那么发光度较低的类星体应该表现出更多的相关吸收。我们表明，强大的无线电源的集群环境与触发这些源中的无线电活动的交互图兼容。最后，我们注意到，如果强大的射电源位于高红移的星团中心，那么它们就是质量是普通星系数百或数千倍的系统的标记。因此，它们的共动数密度的演化严重限制了层次聚类宇宙论。体积，被类星体核光电离。在无线电发射区域内，云的速度分布通过与无线电等离子体的相互作用而增加。那些与射电等离子体强烈相互作用的云可以被撕裂，从而增加了该区域类星体可以光离子化的冷气体的数量。热相通过与无线电等离子体的相互作用而被加热，并且随着无线电等离子体膨胀到热相直至其达到压力平衡，热相也被排除在回流区域之外。冷气体暴露于电离束；因此，即使该体积内气体云的总质量没有变化，更多的气体也会被光电离。这应该会导致此时发射线表面亮度的增加。如果之前未暴露的云核心布满灰尘，那么该区域的物质也可能成为更有效的核辐射散射体。显然，其他因素也会影响云层，例如喷流头部激波锋面的电离。
We discuss the effects of the onset of a powerful Fanaroff - Riley (FR) type II radio source in a central cluster galaxy on the surrounding cluster gas. We show that many observed properties of powerful high-redshift radio sources can be accounted for if the sources are at the centres of clusters with strong cooling flows. The cooling flow provides a ready source of cool and cold gas which can be the source of optical emission- and absorption-line clouds in both quasars and galaxies, along with a means of hiding the central engine in some sources. The. scenario predicts correlations between radio source size and the presence (or lack) of associated optical absorption and the strength of any aligned optical light. In particular, strong Lyoc absorption should be common in radio galaxies; the smaller the region of radio emission, the stronger the absorption. If a large fraction of the associated absorption seen in quasars arises from surrounding cooling flows, less luminous quasars should show considerably more associated absorption. We show that a cluster environment for powerful radio sources is compatible with the interaction picture for the triggering of radio activity in these sources. Finally, we note that if powerful radio sources are at the centres of clusters at high redshift, then they are markers for systems with hundreds or thousands of times the mass of an ordinary galaxy. Consequently, evolution in their comoving number density severely constrains hierarchical clustering cosmologies. volume, photoionized by the quasar nucleus. Within the radio-emitting region, the velocity distribution of the clouds is increased by interaction with the radio plasma. Those clouds strongly interacting with the radio plasma can be ripped apart increasing the amount of cool gas that can be photoionized by the quasar in that region. The hot phase is heated by interaction with the radio plasma, and is also excluded from the backflow region, as the radio plasma expands into the hot phase until it reaches pressure equilibrium. cold gas exposed to the ionizing beam; consequently, much more of the gas is photoionized, even if the total mass in the gas clouds in this volume does not change. This should lead to an increase in emission-line surface brightness at this point. If the previously unexposed cores of the clouds are dusty, then the material in this region could also become far more efficient scatterers of nuclear radiation. Clearly, other factors can affect the clouds, such as ionization by the shock front at the head of the jet.