论文标题
FRII低兴奋的射电星系中的无线电形态形态学模式链接
Radio morphology-accretion mode link in FRII low-excitation radio galaxies
论文作者
论文摘要
Fanaroff-Riley II低兴奋的射电星系（FRII-LEGS）的特征是PC尺度上的核激发弱，以及典型的强大Friis（定义为高兴奋的特性）在KP-SCACALES上的典型特性（定义为高兴奋剂，以下是HERGS/BLRGS）。由于从理论和观察结果上可以期望积聚属性与产生喷气机的力量之间存在联系，因此他们的性质仍在争论中。在这项工作中，我们研究了属于3CR目录的19个Frii-lergs的完整样本的X射线特性，利用Chandra和XMM-Newton档案数据。我们还将32个Frii-Hergs/blrg分析为Chandra数据作为对照样本。我们比较了Frii-lerg和Frii-herg/blrg X射线特性和文献中可用的光学数据，以获得其行为的广泛前景。来自X射线和光条带的Frii-lergs的低积聚率估计值使我们能够牢固地拒绝强大的Frii-hergs/blrgs的高度掩盖。因此，至少可以调用两个假设来解释周五的性质：（i）由于核区域积聚冷气的耗尽，它们正在从经典的弗里斯中演变，而延长的无线电发射是过去有效积累活性的遗产； （ii）它们是相对于经典的弗里斯/弗里斯的本质上不同的对象类别。令人惊讶的是，在这个方向上，积聚率与环境丰富度之间的相关性在我们的样本中发现。富裕的环境，效率越高的是积聚。在此框架中，在增生率和环境方面，Frii-lergs在弗里斯和Frii-hergs/blrgs之间进行了中间。
Fanaroff-Riley II low-excitation radio galaxies (FRII-LERGs) are characterized by weak nuclear excitation on pc-scales and by properties typical of powerful FRIIs (defined as high-excitation, hereafter HERGs/BLRGs) on kp-scales. Since a link between the accretion properties and the power of the produced jets is expected both from theory and observations, their nature is still debated. In this work we investigate the X-ray properties of a complete sample of 19 FRII-LERGs belonging to the 3CR catalog, exploiting Chandra and XMM-Newton archival data. We also analyze 32 FRII-HERGs/BLRGs with Chandra data as a control sample. We compared FRII-LERG and FRII-HERG/BLRG X-ray properties and optical data available in literature to obtain a wide outlook of their behavior. The low accretion rate estimates for FRII-LERGs, from both X-ray and optical bands, allow us to firmly reject the hypothesis for that they are the highly obscured counterpart of powerful FRII-HERGs/BLRGs. Therefore, at least two hypothesis can be invoked to explain the FRII-LERGs nature: (i) they are evolving from classical FRIIs because of the depletion of accreting cold gas in the nuclear region, while the extended radio emission is the heritage of a past efficiently accreting activity; (ii) they are an intrinsically distinct class of objects with respect to classical FRIs/FRIIs. Surprisingly, in this direction a correlation between accretion rates and environmental richness is found in our sample. The richer the environment, the more inefficient is the accretion. In this framework, the FRII-LERGs are intermediate between FRIs and FRII-HERGs/BLRGs both in terms of accretion rate and environment.
