Spatially extended [P II] 1.188μm and [Fe II] 1.257μm emission lines in a nearby seyfert galaxy NGC 1068 observed with OAO/ISLE

Abstract

We present J -band long-slit spectroscopic observation of NGC 1068 classified as a Seyfert 2 galaxy. J -band observations with OAO/ISLE provide clear detection of spatially extended [Fe II] 1.257μmand [P II] 1.188μmlines. We found that [Fe II] 1.257μm=[P II] 1.188μm increases with distance from a central continuum peak. Observed line ratios around the nucleus (continuum peak) are consistent with a typical value expected from photoionization models, while the ratios at 3"-4" (210-280 pc) east and west of the nucleus are slightly higher than this. In the off nucleus region of NGC 1068 we also found a possible association between [Fe II] 1.257μm=[P II] 1.188μm and the radio continuum. This suggests a mild contribution of shock ionization induced by a radio jet outside nucleus while photoionization by the central energy source is dominant near the nucleus. © 2011. Astronomical Society of Japan.