The study of Seyfert 2 galaxies with and without infrared broad lines
  From the literature, we construct from literature a sample of 25 Seyfert 2
galaxies (S2s) with a broad line region detected in near infrared spectroscopy
and 29 with NIR BLR which was detected. We find no significant difference
between the nuclei luminosity (extinction-corrected [OIII]~5007) and infrared
color $\rm{f_{60}/f_{25}}$ between the two populations, suggesting that the
non-detections of NIR BLR could not be due to low AGN luminosity or
contamination from the host galaxy. As expected, we find significantly lower
X-ray obscurations in Seyfert 2s with NIR BLR detection, supporting the
unification scheme. However, such a scheme was challenged by the detection of
NIR BLR in heavily X-ray obscured sources, especially in six of them with
Compton-thick X-ray obscuration. The discrepancy could be solved by the clumpy
torus model and we propose a toy model demonstrating that IR-thin X-ray-thick
S2s could be viewed at intermediate inclinations, and compared with those
IR-thick X-ray-thick S2s. We note that two of the IR-thin X-ray-thick S2s (NGC
1386 and NGC 7674) experienced X-ray transitions, i.e. from Compton-thin to
Compton-thick appearance or vice versa based on previous X-ray observations,
suggesting that X-ray transitions could be common in this special class of
objects.
