Near IR diffraction-limited integral-field SINFONI spectroscopy of the Circinus galaxy

Abstract

Using the adaptive optics assisted near infrared integral field spectrometer SINFONI on the VLT, we have obtained observations of the Circinus galaxy on parsec scales. The morphologies of the H_2(1-0)S(1) 2.12um and Br_gamma 2.17um emission lines are only slightly different, but their velocity maps are similar and show a gradient along the major axis of the galaxy, consistent with rotation.Since V_rot/sigma is approximately 1 suggests that random motions are also important, it is likely that the lines arise in a rotating spheroid or thickened disk around the AGN. Comparing the Br_gamma flux to the stellar continuum indicates that the star formation in this region began almost 10^8 yr ago. We also detect the [SiVI] 1.96um,[AlIX] 2.04um and [CaVIII] 2.32um coronal lines. In all cases we observe a broad blue wing, indicating the presence of two or more components in the coronal line region. A correlation between the ionisation potential and the asymmetry of the profiles was found for these high excitation species.