Near-infrared spectroscopy of Seyfert galaxies for examining the ionization mechanism of narrow-line regions
It is widely believed that the dominant ionization mechanism of narrow-line regions(NLRs)in active galactic nuclei(AGNs)is the photoionization by ionizing photons from the central engine.However it has been sometimes claimed that the fast shock may also contribute to the ionization of gas in NLRs.To discriminate the ionization mechanism of gas clouds in NLRs observationally,the flux ratio of two forbidden emission lines seen in J-band,P Ⅱ 1.188 μm and Fe Ⅱ 1.257 μm,is useful.We report our near-infrared spectroscopic observations of nearby 26 Seyfert galaxies with ISLE near-infrared spectrograph boarded on the 188 cm telescope at Okayama Astrophysical Observatory.As a result,we measured the Fe Ⅱ/P Ⅱ flux ratio or its lower limit for 19 objects.In addition,we collected the flux ratio of 22 Seyfert galaxies from the literature.Based on the collected data,we found that the ionization mechanism of the NLR is the photoionization in most cases but the fast shock contributes in some Seyfert galaxies.The measured Fe Ⅱ/P Ⅱ flux ratio shows no correlation with the radio loudness,indicating that the radio jet is not the main origin of fast shocks in NLRs of Seyfert galaxies.
Koki Terao Tohru Nagao Tetsuya Hashimoto Kenshi Yanagisawa Kenta Matsuoka Hiroyuki Ikeda Yoshiaki Taniguchi
Ehime University National Astronomical Observatory of Japan
国际会议
East-Asia AGN Workshop 2015(2015年东亚活动星系核研讨会)
长春
英文
1-1
2015-07-01（万方平台首次上网日期，不代表论文的发表时间）