Spatially Extended P II 1.188 μm and Fe II 1.257 μm Emission Lines in a Nearby Seyfert Galaxy NGC1068 Observed with OAO/ISLE

摘要

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] 1.257 μm and [P II] 1.188 μm lines. We found that [Fe II] 1.257 μm/[P II] 1.188 μm 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] 1.257 μm/[P II] 1.188 μm 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.