Do AGN triggering mechanisms vary with radio power? - I. Optical morphologies of radio-intermediate HERGs
Do AGN triggering mechanisms vary with radio power? - I. Optical morphologies of radio-intermediate HERGs
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AGN 触发机制是否随无线电功率的变化而变化？
DOI：
10.1093/mnras/stz1253
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发表时间：
2019
影响因子：
4.8
通讯作者：
Pierce J
中科院分区：
文献类型：
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作者：
Pierce J
具有中等射电功率的活动星系核(AGN)能够在星系凸起中驱动多相外流，而且比它们的高射电功率对应的活动星系核更常见。因此，为了更好地了解射电活动星系核反馈在星系演化中的作用，需要深入描述典型的宿主星系和这一群体的可能触发机制。在这里，我们使用深度光学成像数据来研究具有高激发光发射(HERG)谱和中等射电功率的30个局域射电活动星系核的详细宿主形态[z<；0.1；22.5<；log()<；24.0 W Hz-1]。与具有强光学发射线的2Jy射电强星系[LOG()>；25.0 W HZ-1]相比，具有合并和相互作用形态特征的宿主比例大大减少：53%±9.9%，而94%±8.4%。此外，样本中射电最强的一半比射电最弱的一半(分别为67%±112%和40%±113%)有更高的形态扰动频率，其中包括8个受干扰最严重的星系。这表明，通过合并和相互作用在高激发射电星系(HERG)中触发核活动的重要性随着无线电功率的降低而降低。肉眼观察和详细的光线轮廓模型都显示出早期类型和晚期类型的混合形态，这与射电强大的活动星系核所在的巨大椭圆星系相反。晚期宿主的流行可能表明，通过长期的、基于磁盘的过程触发对于无线电功率较低的HERG(例如，磁盘不稳定和大规模条形)具有越来越重要的意义。
Active galactic nuclei (AGNs) with intermediate radio powers are capable of driving multiphase outflows in galaxy bulges, and are also more common than their high-radio-power counterparts. In-depth characterization of the typical host galaxies and likely triggering mechanisms for this population is therefore required in order to better understand the role of radio AGN feedback in galaxy evolution. Here, we use deep optical imaging data to study the detailed host morphologies of a complete sample of 30 local radio AGNs with high-excitation optical emission (HERG) spectra and intermediate radio powers [z< 0.1; 22.5 < log() < 24.0 W Hz-1]. The fraction of hosts with morphological signatures of mergers and interactions is greatly reduced compared to the 2Jy radio-powerful galaxies [log() > 25.0 W Hz-1] with strong optical emission lines: 53 ± 9 per cent compared with 94 ± 4 per cent. In addition, the most radio-powerful half of the sample has a higher frequency of morphological disturbance than the least radio-powerful half (67 ± 12 per cent and 40 ± 13 per cent, respectively), including the eight most highly disturbed galaxies. This suggests that the importance of triggering nuclear activity in high-excitation radio galaxies (HERGs) through mergers and interactions reduces with radio power. Both visual inspection and detailed light profile modelling reveal a mixed population of early-type and late-type morphologies, contrary to the massive elliptical galaxy hosts of radio-powerful AGNs. The prevalence of late-type hosts could suggest that triggering via secular, disc-based processes has increased importance for HERGs with lower radio powers (e.g. disc instabilities and large-scale bars).