Open AccessA disturbed molecular disc in the Circinus galaxy
Author(s) -
Elmouttie M.,
Krause M.,
Haynes R. F.,
Jones K. L.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.t01-1-02002.x
Subject(s) - physics , astrophysics , galaxy , astronomy , radius , star formation , galaxy rotation curve , disc galaxy , active galactic nucleus , molecular cloud , telescope , luminous infrared galaxy , galaxy formation and evolution , stars , computer security , computer science
We have used the Swedish ESO Submillimeter Telescope to observe the molecular gas in the Circinus galaxy using the CO(1 → 0) transition as a tracer. The central region and major axis have been mapped and several other points were also observed. The gas in the galaxy is concentrated towards the nucleus, the peak being coincident with the radio/optical core. The inclination of the molecular galactic disc is more comparable to that of the radio continuum than to that of the large‐scale H i emission. Evidence for an anomalous spur structure pointing radially away from the galactic centre is presented, and may indicate a causal link between it and similar features seen in optical lines and radio continuum. Our data suggest the presence of a central molecular ring or disc with radius 300 ± 50 pc and a rotation velocity of about 200 km s −1 (assuming i = 73°). The dynamical mass of the nucleus is estimated to be no greater than 3.9 × 10 9 M ⊙ . Assuming that the distribution of gas varies smoothly in the outer regions, we calculate the mass of molecular gas in the galaxy to be at least M mol = 1.1 × 10 9 M ⊙ , and the star‐forming efficiency to be 11 ± 2 L ⊙ M ⊙ −1 . These results imply that Circinus is undergoing a massive central starburst which may be, at least partially, responsible for its extended minor axis emission seen in several wavebands.