λ = 2 mm spectroscopy observations toward the circumnuclear disk of NGC 1068
Abstract
Aims: We investigate the physical and chemical conditions of molecular gas in the circumnuclear disk (CND) region of NGC 1068.
Methods: We carried out a spectral line survey with the IRAM 30 m telescope toward the center of NGC 1068 and mainly focused on the 2 mm band with a frequency coverage of 160.7-168.6 GHz and 176.5-184.3 GHz.
Results: Fifteen lines are detected in NGC 1068, eight of which are new detections for this galaxy. We derive the rotation temperatures and column densities of fourteen molecular species.
Conclusions: Based on the [HCO+ (2 - 1)]/[HOC+ (2 - 1)] ratio, we obtain a high ionization degree in the CND of NGC 1068. It is found that HC3N is concentrated in the east knot, while 13CCH, CH3CN, SO, HOC+, CS, CH3CCH, and H2CO are concentrated in the west knot. Compared to the star-forming galaxies M 82 and NGC 253, the chemistry of NGC 1068 might be less strongly affected by the UV radiation field, and its kinetic temperature might be lower.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2020
- DOI:
- 10.1051/0004-6361/201935800
- arXiv:
- arXiv:2001.08697
- Bibcode:
- 2020A&A...634A.125Q
- Keywords:
-
- ISM: molecules;
- galaxies: ISM;
- galaxies: individual: NGC 1068;
- galaxies: nuclei;
- galaxies: active;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 28 pages, 10 figures