MILLIMETER LINE CO(2-]1) OBSERVATIONS OF A COMPLETE SAMPLE OF AGN

Citation
D. Rigopoulou et al., MILLIMETER LINE CO(2-]1) OBSERVATIONS OF A COMPLETE SAMPLE OF AGN, Astronomy and astrophysics, 327(2), 1997, pp. 493-502
Citations number
37
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
00046361
Volume
327
Issue
2
Year of publication
1997
Pages
493 - 502
Database
ISI
SICI code
0004-6361(1997)327:2<493:MLCOOA>2.0.ZU;2-E
Abstract
We report on observations of the CO (2-->1) transition of a complete s ubset of 11/39 of the Piccinotti (1982) hard X-ray selected AGN sample . All of the 11 galaxies were clearly detected. All the galaxies in ou r sample are strong hard-X ray sources and thus the sample is unbiased with respect to obscuring material. Six of the galaxies are Seyfert 1 type objects with the rest five being reddened Seyfert Is, or the so called ''Narrow Line Galaxies''. Based on our high S/N detections we i nvestigate the relation between CO and far-infrared luminosities. A st rong correlation is found to exist for both Seyfert Is and Narrow Line Galaxies similar to the one seen in normal and bright infrared galaxi es. Our data also suggest that the FIR emission in Seyferts galaxies i s of thermal origin, an argument which is supported by three different lines of evidence, the CO-FIR correlation, the FIR/M(H-2) dependence on dust temperature and the similarities in the shapes of the CO and H I profiles. The relation between CO emission and non-thermal radio pow er was examined next. Seyferts were found to show an excess radio non- thermal power for a given CO luminosity (when compared to starburst ga laxies) while no differences were found between Seyfert Is and 2s in t heir CO and radio properties (Seyfert 2s were selected from the litera ture). We conclude that Seyfert Is and Narrow Line Galaxies have very similar properties with respect to their molecular gas reservoir. By c omparing our CO observations with published optical data we explore th e distribution of the molecular clouds in the sample galaxies. We find that in most cases the spatial distribution of CO clouds is confined within 1-1.4 kpc around the nucleus.