• DOI:10.1088/0004-637X/730/2/121
• Corpus ID: 119209693

The Different Nature of Seyfert 2 Galaxies With and Without Hidden Broad-line Regions

@article{Wu2011TheDN,
  title={The Different Nature of Seyfert 2 Galaxies With and Without Hidden Broad-line Regions},
  author={Yu-Zhong Wu and En-peng Zhang and Yan-chun Liang and Cheng-min Zhang and Yongheng Zhao},
  journal={The Astrophysical Journal},
  year={2011},
  volume={730},
  pages={121}
}

• Yu-Zhong Wu, E. Zhang, +2 authors Yongheng Zhao
• Published 21 January 2011
• Physics
• The Astrophysical Journal

We compile a large sample of 120 Seyfert 2 galaxies (Sy2s) which contains 49 hidden broad-line region (HBLR) Sy2s and 71 non-HBLR Sy2s. From the difference in the power sources between two groups, we test whether HBLR Sy2s are dominated by active galactic nuclei (AGNs) and whether non-HBLR Sy2s are dominated by starbursts. We show that (1) HBLR Sy2s have larger accretion rates than non-HBLR Sy2s; (2) HBLR Sy2s have larger [Ne V] λ14.32/[Ne II] λ12.81 and [O IV] λ25.89/[Ne II] λ12.81 line ratios than non-HBLR Sy2s; and (3) HBLR Sy2s have smaller IRAS f 60/f 25 flux ratios, which show the relative strength of the host galaxy and nuclear emission, than non-HBLR Sy2s. Consequently, we suggest that HBLR Sy2s and non-HBLR Sy2s are AGN dominated and starburst dominated, respectively. In addition, non-HBLR Sy2s can be classified into luminous (L [O III]>1041 erg s–1) and less luminous (L [O III] < 1041 erg s–1) samples, when considering only their obscuration. We suggest that (1) the invisibility of polarized broad lines (PBLs) in the luminous non-HBLR Sy2s depends on the obscuration and (2) the invisibility of PBLs in the less luminous non-HBLR Sy2s depends on the very low Eddington ratio rather than the obscuration.