OAO/ISLE Near-IR Spectroscopy of IRAS Galaxies

We present the results of the near-infrared (IR) spectroscopy of nine IRAS galaxies (NGC.1266, NGC 1320, NGC 2633, NGC 2903, NGC 3034, Mrk 33, NGC 7331, NGC 7625, NGC 7714) with the ISLE imager and spectrograph mounted on the Okayama Astrophysical Observatory 1.88-m telescope. [Fe II] 1.257 mu m and Pa beta emission lines were observed for the whole sample, while H-2 2.121 mu m and Br gamma lines were additionally obtained for two sources, whose flux ratios were used as a diagnostic tool of dominant energy sources of the galaxies. We found that the nucleus of NGC 1266 is most likely a low-ionization nuclear emission-line region (LINER), while NGC 2633 and NGC 2903 possibly harbor active galactic nuclei (AGNs). No AGN or LINER signal is found for other objects. In addition, we found the spectral features, which are indicative of some unusual phenomena occurring in the galaxies, such as the large [Fe II] line widths compared to the local escape velocity in NGC 1266. The present work shows the potential ability of ISLE to shed new light on the nature of infrared galaxies, either through a statistical survey of galaxies or an exploration of spectral features found in individual objects.