Imaging carbon monoxide emission in the starburst galaxy NGC 6000

Abstract

We present measurements of carbon monoxide emission in the central region of the nearby starburst NGC 6000 taken with the Submillimeter Array. The J = 2-1 transition of 12CO, 13CO, and C18O were imaged at a resolution of 3″ × 2″ (450 × 300pc). We accurately determine the dynamical center of NGC6000 at αJ2000.0 = 15h49m495 and δJ2000.0 = -29°23′13″ which agrees with the peak of molecular emission position. The observed CO dynamics could be explained in the context of the presence of a bar potential affecting the molecular material, likely responsible for the strong nuclear concentration where more than 85% of the gas is located. We detect a kinematically detached component of dense molecular gas at relatively high velocity which might be fueling the star formation. A total nuclear dynamical mass of 7 × 109M is derived and a total mass of gas of 4.6 × 108M, yielding a M gas/M dyn 6%, similar to other previously studied barred galaxies with central starbursts. We determined the mass of molecular gas with the optically thin isotopologue C18O and we estimate a CO-to-H 2 conversion factor X CO = 0.4 × 1020 cm-2(K km s-1)-1 in agreement with that determined in other starburst galaxies. © 2010. The American Astronomical Society. All rights reserved.