A treatment procedure for VLT/SINFONI data cubes: application to NGC 5643

TL;DR

This paper introduces a data cube treatment procedure for VLT/SINFONI observations, enhancing image quality and revealing detailed structures of ionized and molecular gas around NGC 5643's nucleus, supporting the unified AGN model.

Contribution

The paper presents a novel data processing method for VLT/SINFONI data cubes that significantly improves image clarity and enables detailed analysis of nuclear gas structures.

Findings

Enhanced image quality reveals ionized and molecular gas clouds.

Ionized gas forms a bicone consistent with the narrow-line region.

Morphologies support the presence of a molecular torus/disc feeding the AGN.

Abstract

In this second paper of a series, we present a treatment procedure for data cubes obtained with the Spectrograph for Integral Field Observations in the Near Infrared of the Very Large Telescope. We verified that the treatment procedure improves significantly the quality of the images of the data cubes, allowing a more detailed analysis. The images of the Br$\gamma$ and H$_2 \lambda 21218$ emission lines from the treated data cube of the nuclear region of NGC 5643 reveal the existence of ionized and molecular-gas clouds around the nucleus, which cannot be seen clearly in the images from the non-treated data cube of this galaxy. The ionized-gas clouds represent the narrow-line region, in the form of a bicone. We observe a good correspondence between the positions of the ionized-gas clouds in the Br$\gamma$ image and in an [O III] image, obtained with the Hubble Space Telescope, of the nuclear region of this galaxy convolved with an estimate of the point-spread function of the data cube of NGC 5643. The morphologies of the ionized and molecular gas seem to be compatible with the existence of a molecular torus/disc that collimates the active galactic nucleus (AGN) emission. The molecular gas may also flow along this torus/disc, feeding the AGN. This scenario is compatible with the unified model for AGNs.