标题： 发光的射电明亮活动星系核是否由星系相互作用触发？ 显示英文标题

标题： Are luminous radio-loud active galactic nuclei triggered by galaxy interactions?

摘要： 我们展示了在中等红移（0.05<z<0.7）下，46个南天2Jy射电星系的光学形态与两个静止早型星系控制样本的比较结果：来自耶鲁明亮椭圆星系观测（OBEY）调查的55个低红移（z<0.01）椭圆星系，以及扩展格罗思条带（EGS）中红移为0.2<z<0.7的107个早型星系。基于这些比较，我们讨论了星系相互作用在触发强大射电星系（PRGs）中的作用。我们发现，在低红移和中等红移下，相当一部分静止椭圆星系在相对较高的表面亮度水平上显示出扰动形态的证据，这可能是过去或正在进行的星系相互作用的结果。然而，在PRGs星系宿主中检测到的形态特征（例如潮汐尾、壳层、桥等）比其静止对应物中的要亮约2个星等。事实上，如果考虑相同的表面亮度限制，静止星系群体中的扰动形态比例明显较小（在z<0.2时为53%，在0.2<z<0.7时为48%），而PRGs中则较高（在z<0.2时为93%，在0.2<z<0.7时为95%，仅考虑强线射电星系）。这支持了一个场景，即PRGs代表了一部分近期经历合并/相互作用的椭圆星系的短暂活跃阶段。然而，我们证明只有很小一部分（<20%）的扰动早型星系能够容纳强大的射电源。 显示英文摘要

摘要： We present the results of a comparison between the optical morphologies of a complete sample of 46 southern 2Jy radio galaxies at intermediate redshifts (0.05<z<0.7) and those of two control samples of quiescent early-type galaxies: 55 ellipticals at redshifts z<0.01 from the Observations of Bright Ellipticals at Yale (OBEY) survey, and 107 early-type galaxies at redshifts 0.2<z<0.7 in the Extended Groth Strip (EGS). Based on these comparisons, we discuss the role of galaxy interactions in the triggering of powerful radio galaxies (PRGs). We find that a significant fraction of quiescent ellipticals at low and intermediate redshifts show evidence for disturbed morphologies at relatively high surface brightness levels, which are likely the result of past or on-going galaxy interactions. However, the morphological features detected in the galaxy hosts of the PRGs (e.g. tidal tails, shells, bridges, etc.) are up to 2 magnitudes brighter than those present in their quiescent counterparts. Indeed, if we consider the same surface brightness limits, the fraction of disturbed morphologies is considerably smaller in the quiescent population (53% at z<0.2 and 48% at 0.2<z<0.7) than in the PRGs (93% at z<0.2 and 95% at 0.2<z<0.7 considering strong-line radio galaxies only). This supports a scenario in which PRGs represent a fleeting active phase of a subset of the elliptical galaxies that have recently undergone mergers/interactions. However, we demonstrate that only a small proportion (<20%) of disturbed early-type galaxies are capable of hosting powerful radio sources.